Science - Teachers Sri Lanka

mytutor.lk

Science - Teachers Sri Lanka

SCIENCE

Teacher Instruction Manual

Chemistry & Physics

Copyright © 2007 National Institute of Education - Sri Lanka. All rights reserved.

Grade 10

2007

Department of Science, Health & Physical Education

Faculty of Science &Technology

National Institute of Education


Science

Grade 10

Chemistry & Physics

2007

Copyright © 2007 National Institute of Education - Sri Lanka. All rights reserved.

© National Institute of Education

ISBN-

Department of Science, Health & Physical Education,

Faculty of Science &Technology,

National Institute of Education.

Printing:

NIE Press,

National Institute of Education,

Maharagama.

i


Message of the Director General

The first curriculum revision for the new millennium is based on the elimination of the several

problems obtaining in the present education system. The present curriculum reforms have been

planned having identified the problems that youth face consequent to the weakening of their

thinking abilities, social abilities as well as personal abilities and step by step exploration of

factors leading to this situation, to overcome which, the necessary background was prepared.

Compared to the other countries in the Asian region, our country took the lead in education in

earlier years. But most countries in this region have superceded Sri Lanka in education today.

Some factors that influenced this deterioration are the action taken by educational institutions to

continue to take action to confirm the known, learn that which had been decided on earlier, and

reconstruct that which was, in the same form itself.

All these matters have been taken into consideration and the officers of the National Institute of

Education have endeavoured to prepare the new curriculum on the basis of a distinct philosophy.

The primary objective here is to change that which is known, explore that which is new and

develop that which is necessary for tomorrow and build up a generation of students who can

display their readiness for a successful future. But there is no need to reiterate, the need for a

visible change in the teacher’s role for the realization of this objective. In place of the obvious

transactional teacher role presenting in our classrooms so far, the Sri Lankan school teacher will

have to understand and conform to a student-centered, competency based and activity focused

transformational role.

It is our firm belief that this Teacher Instruction Manual will serve you as an aid to become an

effective teacher through the provision of numerous instructions that will help you adapt to the

new situation. Through the study of these instructions you will be provided the opportunity of

making your daily teaching as well as the evaluation task easy. There is no doubt that instructions

for student exploration and other quality inputs will help facilitate the teacher’s task. Similarly,

the Teacher Instruction Manual will help convey to school principals valuable information they

can use in time-tabling, sharing of limited resources and internal supervision.

My sincere thanks go to Dr. Mrs. I. L. Ginige, Assistant Director General (Curriculum

Development) Science & Technology Faculty of National Institute of Education for her direct

involvement in the preparation of this Teacher Instruction Manual that will serve an immense

purpose in the task performed at school level by the section above and also teacher educationist

involved in beginning or continuous teacher educational matters, in-service advisors as well as

officers at various levels, involved in external supervision plus monitoring programmes.

Professor J. W. Wickramasinghe

Director General

National Institute of Education

iii


Preface

The first curriculum reform for the millennium implemented with the aim of preparing a

powerful basis for a new Sri Lanka anticipates a visible transformation of the teacher’s role. The

three main sections below are included in the Teacher Instruction Manual prepared with the

objective of providing the teacher with the necessary support in this regard.

· Detailed Syllabus

· Activity Continuum that helps in the implementation of the syllabus

· Instruments for the extension of the learning teaching process.

Teachers have been provided the opportunity of understanding several basic matters that

have been taken into consideration in the preparation of the curriculum for the detailed syllabus

extending beyond subject topics and sub-topics. Competency levels that correspond to subject

competency have been included in this section that commences with an introduction to the factors

and subject aims that formed the basis of the new syllabus. One special features of this section is

that, while the knowledge-base determined under competency level each student needs to develop

has been introduced as the subject content the multiple learning and teaching methods employed

in transmitting this section to the student has also been taken into consideration in determining the

time frame with respect to each competency level.

The final part of the detailed syllabus presented under the heading “School Policy and Programs”

needs to be studied very carefully and understood by every instructional leader. This section

provides school managers a range of valuable instructions to assist them in the allocation for

teaching, subject-teaching assigning functions to teachers, implementing co-curricular activities

as well as supervision of the teacher’s task. The second section of the Teacher Instruction Manual

has been prepared with the objective of providing teachers with clear understanding of the proposed

learning- teaching methodology. This section commences with the introduction of the methods of

planning activities under competency-based education as well as the change in the teacher’s role.

Although the activity continuum necessary for the implementation of the curriculum has been

introduced next, the implementation of the proposed activity in the very same manner is not

expected of teachers. The teacher should endeavor to make use of his / her creative, as well as

critical thinking abilities and adapt these activities in a manner that suits ones class, best. Although

instructions have been provided on the constitution of groups in keeping with the facets of the

problems subject to exploration, the teacher is expected to take an intelligent decision on the

number of groups based on number of students in the class.

iv


Time has been allocated for activities to ensure achievement of the relevant competency levels.

Therefore, teachers may have to exceed the 40-minute period. While each activity has been

provided adequate time for the actualization of each competency level, the teacher is expected

to make use of single or double periods in the time table and breakdown these activities, as

suitable in implementing them.

For the success of the procedure it is essential that every time an activity commenced the previous

day is carried over to the following day, that a brief summary of the part of the activity completed

the previous day is presented to the class. Similarly, this decision will provide the school community

with the opportunity of involving students in effective learning where teachers obtain leave of

absence.

The final item in this section is a list of quality inputs necessary for the maintenance of the quality

of subject learning and teaching, when taken as a whole. As such, the teacher has a choice of

ordering out the necessary learning-teaching materials in time and having them on hard.

Included in the third part of the teacher Instruction Manual under the title

“ Assessment and evaluation” are a number of important hints to ensure that the expected results

of the exercise are realized.

This section has been so structured as to introduce matters related to the assessment and evaluation

that should take place under each activity, extension of the learning and teaching that takes place

based on activity groups and the nature of the questions that might be expected in general

examinations. It must be pointed out that the primary responsibility of the teachers is to Identify

instances where assessment and evaluation can be implemented in the course of each activity

and to carry out this task successfully on the basis of common criteria. The set of instruments

prepared with a range of activities as the objective for the purpose of extending learning and

teaching provide students with the opportunity of involvement in continuous learning outside the

recommended classroom sessions. While it is the task of the teacher to regularly examine the

learning students receive, based on these instruments, and encourage them, arriving at a correct

decision regarding the final results of the activities and communicating that decision to the relevant

parties is expected of the teacher. It is essential that a visible change takes place in general

examinations for the success of the learning-teaching process. The National Institute of Education,

with the assistance of the Sri-Lanka Department of Examinations, has introduced several prototype

questions for educational levels that terminate with these examinations. Since this change in

examination question papers has been suggested in order to direct students to learn through

practice and experience, instead of resorting to mechanical approaches like memorizing or

answering model question papers, the education of school students and parents about this change

should commence at the beginning itself.

v


All teachers should realize that various activities can be developed for the achievement of any

particular competency level. Accordingly, they should be prepared for more successful teaching

through the use of better approaches, exploration, as well as instruments for the extension of

learning and teaching.

The present Teacher Instruction Manual will give teachers right throughout the country the courage

to effect a visible change in the teacher’s role and prevent their becoming inactive in the presence

of new approaches. Similarly, we expect to award certificates and provide numerous development

opportunities to teachers who go beyond the activities to involve themselves in the innovation of

novel creations. What teachers have to do order in to become eligible to the awards is to improve

these activities, using their creative thinking, and present them. Learning-teaching plans prepared

in this manner outside the basic activity plan, should be forwarded to Assistant Director General

( Curriculum Development ), Science and Technology faculty, National Institute of Education,

Sri Lanka. Selection of those entitled to awards will be made subsequent to the study of these

activities by the relevant subject committees.

We have endeavoured in this manner, to bring learning-teaching assessment and evaluation on to

the same platform through new methodologies. According to this, teachers will be provided

substantial latitude to meaningfully handle the learning-teaching process, school-based assessment,

as well as assignment of home-work. It is our firm conviction that the school system of Sri Lanka

will, make maximum use of this aid and depart from orthodox learning-teaching approaches to

enhance the thinking abilities, social abilities as well as the individual abilities of the sons and

daughters of the county.

Dr. Indira Lilamani Ginige

Assistant Director General (Curriculum Development),

Faculty of Science and Technology ,

National Institute of Education,

Sri Lanka.

vi


Direction:

Prof. J W Wickremasinghe - Director General

Guidance:

Dr. I. L. Ginige

Assistant Director General

Faculty of Science and Technology

National Institute of Education

Supervision :

Mr. C M R Anthony

Director

Department of Science, Health & Physical Education

Instructional leadership, Co-ordination and Editing :

Mr. C M R Anthony - Director

Mr. G H Gauthamadasa - Chief Project Officer

Mr. W A D Rathnasuriya - Chief Project Officer

Mr. W A Sumathipala - Project Officer

Ms.J Athamlebbe - Project Officer

Mr. A D A de Silva - Project Officer

Mr. L K Waduge - Project Officer

Mr. P Malavipathirana - Project Officer

Ms. Nadee Ama Jayasekera - Project Officer

Ms. H M Mapagunaratne - Asst. Project Officer

Translation : Mr. R.B.A.Jayasekara

Computer page setting : Mr. K.Wimalasena, Mahinda College, Galle.

Art : Ms. U L N Fernando

Teacher Service,

Sirimavo Bandaranayake BV. Colombo.07.

Cover page and pictures : Master. Soraj Dhananjaya Kolonne,

Grade 11, Thurstan College, Colombo.

vii


Contents

Page

² Director General’s Message iii

² Preface iv

² Contributors vi

² Contents vii

² School Policies and Progammes 15

Copyright © 2007 National Institute of Education - Sri Lanka. All rights reserved.

· Learning-Teaching Methodology

² Introduction 18-20

² Quality Inputs 21

² Activity Continuum 22-114

· Assessment and Evaluation

² Introduction 117-118

² Tools for Extended Learning 119 -124

² Prototype Questions 125 -129

viii


Competency 1.0 ( Investigates Scientific findings about

structure of matter and quantity

Copyright © 2007 National Institute of Education - Sri Lanka. All rights reserved.

Competency level 1.1 ( Discuss the scientific findings about the structure of

atom.

Activity 1.1 ( Let us go inside the atom.

Time ( 120 minutes

Quality inputs ( ² Photograph of a nuclear reactor.annex 1.1.1

² Three copies of instructions for exploration given in

annex 1.1.2

• ² Three copies of the article"Let us get inside

the atom"annex 1.1.3

² Demy papers and pastels

Teaching-learning process (

Step 1.1.1 ( ² Display the photograph to the class.

² Inquire from the children as to what know about what is

given in the picture

² Conduct a brain storming discussion to highlight the

following.

That,

² In an atomic reactor,the energy in the atoms is

transformed into energy that is useful to man.

² atom is the building blocks of matter.

² The findings about the atom can be made use of for the

benefit of man.

(15 minutes)

Step 1.1.2 ( ² Divide the class into three groups.

² Provide the groups with copies of instructions for

exploration.

² Assign the tasks and engage the groups in exploration.

² Prepare them to present their findings to the class.

(60 minutes)

Step 1.1.3 ( ² Get each group to present their findings to the class.

² Give the first opportunity to the respective group to

elaborate on the presentation.

² Get the other groups to propose constructive sugges

tions,

² Elaborate highlighting the following points.

9


Copyright © 2007 National Institute of Education - Sri Lanka. All rights reserved.

That,

² Atom is a particle with a small mass.

² Fundamental sub atomic paticles inclued in an atom

are electrons,protons and neutrons.

² Out of the paticles the lightest particle is the

electron.

² mass of an electron is about 9.1095x 10 -31 kg

² electron is a particle with a negative charge.

² Scientists J.J Thompson,Millikan Cotributed to the

fundamental studies about the electron .

² Proton is a partical having a mass of about 1840

times the mass of an electron.

² Mass of a proton is about 1.6725x10 -31 kg

² Proton is a particle with a positive charge.

² Proton is symbolised as 1 p 1

² Ernest Rutherford contributed to the fundamental

studies about the proton.

² Neutron is a partical which has a mass almost equal

to that of a proton.

² Mass of a neutron is about 1.6750x10 -20 kg.

² Neutron is a particle with no charge,it is neutral.

² Neutron is symbolised as 1 n 0

² The number of electron or the number of protons in

an atom of an element is identical to that element.

² According to J.J Thompasons"Plum pudding "model

he stated that an atom is a sphere which is positively

charged,and the electrons which are negatively

charged are embeded in it.

² According to Rutherford solar model the protons,and

neutrons are collected at the centre which is the

nucleus and the electrons are moving in orbits around

it.

² These shells are named as K.L.M.N from centre

out wards

(45 mts)

10


Criteria for assessment and evaluation

² Names and describe the fundamental sub atomic particles.

² Appreciates that scientists have contributed to the findings about the atomic structure.

² Compare different atomic models.

² Collect data about scientific discoveries using references.

² Present fact in an alternative way.

Annex 1.1.1

Copyright © 2007 National Institute of Education - Sri Lanka. All rights reserved.

a

11


Copyright © 2007 National Institute of Education - Sri Lanka. All rights reserved.

Instructions for group exploration

² Given below are three types of sub atomic particles in an atom.

² Electron

² Proton

² Neutron

² Focus your attention on the sub atomic particle relevant to you.

Annex 1.1.2

² With reference to the reading material provided to you discuss the follwing about the sub

atomic particle relevant toyou.

² It`s discovery

² Properties

² How it is placed in the atom according to different atomic models.

² Be prepared to present your findings to the class.

Annex 1.1.3

Let us go inside the atom

Atom is derived from the Greek word "atomos" which means ,not divisible further

but later it was discovered that it is made up sub atomic particles.Although there are many Sub

atomic particles only three important particles are mentioned below.

1& Electron

In the middle of the nineteenth century Scientists drew their attention whether

it is possible to conduct through gases

In 1875 B.C Crooks observed that in a closed glass tube with ends having two

electrodes and a high voltage is applied and in the meantime the air pressure inside to tube is

gradually reduced,there is a glow near the cathode.Further he noticed that if the air pressure is

further reduced this glow gradually move from the cathode towards the anode,and that there is

a"shadow" between the cathode and the anode.When the pressure inside the tube is about 1

pascall he noticed that the shadow got distributed throughout the tube and that there is an

emission of a beam of rays from the cathode to the anode.Since these rays were emitted from

the cathode they were named as cathode rays by crooks.This set up is called the cathode ray

tube.

In (1858BC-1940BC) J.J.Thompson conducted further experiments with these

rays,As a result of these experiments following conclusions were arrived at about the properties

of cathode rays.

1 Cathode rays move in straight lines.

2 They are negatively charged

3 They are made up of particles having a mass.

12


Copyright © 2007 National Institute of Education - Sri Lanka. All rights reserved.

J.J.Thompson conducted an experiment to determine the (e/m ) ratio of the cathode ray

particales, where (e) is the charge and (m) is the mass.

The value he got for e/m was very large

e/m=1.76x10 c kg -1

The values obtained for e/m ratio for the cathode rays using different gases and different cathodes

is the same.By this Thompson concluded that the cathode rays consists of the same

particles.Further Thompson stated that,the fundamental unit of electricity,the electron introduced

by J.J. Stony in 1874 B.C.is the negatively charge particles in the cathode rays.

Electron is a common sub atomic particle present in all atoms.

Charge of an electron = 1.602x10 -19 C

Mass of an electron = 9.1095x10 -31 kg

At present different forms of cathode ray tubes are used in various electronic instruments.

Some of these are TV photo tube,Computer monitor,Cathode ray Oscilloscope,

Fluorescent tube

Proton

Cathode

High Voltage

To Vaccum Pump

Simple Cathode Ray Emitting Tube

Anode

In 1886 B.C. E.Goldstien observed that when using a porous Cathode,is subjected to a voltage

from 20,000V to 50,000V some special rays were seen to emit from the pores in the Cathode in

a direction opposite to the Cathode rays.He named them as positive rays.

When ratio e/m was calculated for the particles in these positive rays it was found that the value

is numerically smaller to that of the particles in the cathode rays.

When different gases were used in the Cathode ray tube the e/m ratio for the particles in the

possitive rays were found to be whole numerical multiples of the e/m ratio for the particles in the

possitive rays.When Hydrogen gas is used in the cathode ray tube.In short the lightest possitive

rays particles were obtained from Hydrogen.In 1871 B.C-!937B.C Rutherford,named this lightest

possitive ray particle as proton and also that it should be the common possitively charged fundamental

particle of all matter.

Charge of a proton=1.602x10-19C

Mass of a proton=1.6726x10-27 Kg

Mass of a proton is 1840 times the mass of an electron.

13


High Voltage

Cathode with a slit

Anode

production of possitive rays

Neutron

Possitively charged particles named α particles are emitted from radio active sources.When

fall on to the instrument to detect charged particals, it causes a deflection.(Fig. a)

In 1932 James Chadwick conducted an experiment form which it was founded that when a

thin Berylium sheet was place in between the radio active source and the detector no deflection

was seen ( Fig. b)

When a paraffin sheet was place between the Berylium α

sheet and the detector tere was a

deflection. (Fig. c)

Source of

Detector

particals

(a)

(b)

(c)

Berylium plate

Berylium plate

particals

Paraffin wax plate

Shows deflection

Possitive charge

particals fall on

detector

No deflection is

shown

charged particals are

not falling on the

detector

Shows a deflection

charged particals

fall on the detector

Chargeless Neutrons Particals with possitive charge

(d)

14


Chadwick showed that when α Particles strikes the beryllium sheet it releases particles which

has no charge.When these particles strikes the paraffin sheet,it releases charged particles and

as a result there is a deflection in the detector.(Figd)

He also found that when particles strikes the beryllium sheet,the uncharged particles emitted

from it has a mass equal to that of the Hydrogen atom. He stated that these particles are another

type of sub atomic particles and named them as neutrons.

mass of a neutron = 1.6750x10 -27 kg

Copyright © 2007 National Institute of Education - Sri Lanka. All rights reserved.

Thompsons` Atomic Model(Plum pudding model)

α

Rutherford`s model of the atom(Solar model)

Using rays emitted by radioactive material,in 1911 Geiger and Marsden conducted an

experiment to find the στρucture of matter under the direction of Rutheford.Here a beam of

particles was obtained using radio active polonium kept in a lead chamber with a slit.In this

experiment a thin gold foil was bombarded with particles.They kept a screen painted with Zinc

sulphide to detect the direction in which the particles move.There was a glow when

particles struck the Zinc sulphide sheet.

Rutherford's gold leaf experiment

Source of Polonium

Thin gold leaf

Led block with the hole

Zinc Sulphide

screen which

could move

around the

gold leaf

15


In this experiment it was discovered that most of the Alpha particals went through the gold foil

without any deviation, a small number of Alpha particals deviated when going through the gold

foil and a very small number were reflected. The reason why most of the Alpha particals went

through without any difficulty was because according to Rutherford a major part of an atom is

empty space.

Atom

α particals

Nucleis

Copyright © 2007 National Institute of Education - Sri Lanka. All rights reserved.

Reflected

particals

Model to explain the results of Rutherfords experiment

particals not diverging

particals diverging

Further according to Rutherford possitively charged α particles some deviated and some reflected

because there are small areas inside atom where possitive charges are collected together.These

possitively charged areas he called nucleui.Later Rutherford Put forward a theory according

which he says,electrons are revolving in circular orbits around the nucleus,like the planets are

revolving round the sun.

electron

nucleus

path

16


Competency 1.0 ( Investigates Scientific findings about

structure of matter and quantity

Copyright © 2007 National Institute of Education - Sri Lanka. All rights reserved.

Competency level 1.2 ( Use Scientific Conventions to highlight diversity in

atoms

Activity 1.2 ( Let us Investigates about atoms, make models, study about

diversity.

Time ( 120 minutes

Quality inputs ( ² Poster showing the planetary modle structure of Helium

and Sodium included in annex 1.2.1

² Four copies of instructions for exploration given in

annex 1.1.2

² Four copies of the article"Looking at an atom with an

exploratory eye", included in annex 1.2.3

² Beads of three colours or small rigifoam balls.,bucket

wires,gum,ekle and thread

² Demy papers and pastels

Teaching-learning process (

Step 1.21 ( ² Display to the class the poster showing the structure of

Helium and Sodium atoms.

² Conduct a brain storming session to highlight the

following.facts.

That,

² The shells in an atom from nucleus outwards are named

K, L, M, N

² Helium atom has two electrons in the K shell

Sodium atom has K, L, M, Shells with 2,8,1 electrons

respectively.

• ² The highest number of electrons K,L,M,N shells could

have is 2, 8, 8,18

² The arrangement of electrons in the shells around the nucleus

of an atom is called electronic configuration

² The electronic configuration of an atom is one

convention which indicate the identify of an atom.

(15 minutes)

17


Copyright © 2007 National Institute of Education - Sri Lanka. All rights reserved.

² Provide the class with copies of instructions for

exploration.material for making models,the letter,demy

paper and pastel

² Assign the tasks and engage the groups in exploration.

² Prepare them to present their findings to the class.

(60 minutes)

Step 1.2.3 ( ² Get each group to present their findings to the class.

² Give the first opportunity to the respective group to

elaborate on the presentation.

² Get the other groups to propose constructive sugges

tions,

² Elaborate highlighting the following points.

That,

² In Chemistry there are 110 elements discovered at

present.

² Every elements is symbolized using the letters in the

English Alphabet.

² Atomic number is the number of protons in the

nucleus of the atom.

² In a neutral atom the number of electrons(-

charges)and the number of protons (+chargs) are

equal.

² In the atomic nucleus both types of sub atomic

particles,protons and neutrons are present.

² In an element the number of protons is constant. But

there are atoms with varying number of neutrons.

² The total number of Protons and neutrons in the

nucleus of the atom is called the mass number or the

number of nucleons.

² Atoms of an element having identical number of

protons but different number of neutrons the mass

number varies.These atoms are called isotopes.

² In a chemical symbol of an atom on the top left side is

the mass number and at bottom is the atomic

number. (

12 6

C )

² The relative mass of an atom is the number of times

the mass of the atom relative to 1/12 of the mass of

12

6

C isotope atom.

18


² Relative atomic mass=mass of an atom of an element/massof

12

6C

isotope atomx 1/12

(45 minuts)

Criteria for assessment and Evaluation

² Names and describe conventions related to identification of elements.

² Appreciates that diversity of matter is built on diversity of atoms.

² Contruct models to show the structure of atoms.

² Show diversity by using Symbols.

² Discover facts using various Sources.

Copyright © 2007 National Institute of Education - Sri Lanka. All rights reserved.

Arrangement of sub - Atomic particals in Helium and Sodium

He Atom

Na Atom

²

²

²

² ²²

² ²²

²

K Shell Electronic configuration 2

²

K Shell

L Shell

M Shell

Electronic configuration 2" 8" 1

19


Annex 1.2.2

Instructions for group exploration

² Focus your attention to the six atoms assigned to your group, according to the table given

below.

Data of some atoms

Symbol

(not the

standard )

A B C D E F G H I J K L M N O P Q R S T U V W X

Copyright © 2007 National Institute of Education - Sri Lanka. All rights reserved.

Number of

Protons

1 4 1 12 17 19 2 6 7 13 6 18 3 8 11 8 15 20 5 9 10 14 10 16

Number of 1 4 1 12 17 19 2 6 7 13 6 18 3 8 11 8 15 20 5 9 10 14 10 16

Electrons

Number of 1 5 2 12 18 20 2 6 7 14 7 22 4 8 12 9 16 20 6 10 10 1412 16

Neutrons

Group i Group ii Group iii Group iv

² Using data given in the table and the artical " Looking at the atom with an exploratory eye"

find the standard chemical symbols to the elements provided to you.

² Find the atomic mass and mass number of the atoms provided to you by using the types of

sub atomic particals and their numbers.

² Develope the eletronic configuration of the respective elements by writing the number of

eletrons in the cells from closer to the nucleus outwards.

² Develope using the letter discuss about isotopes and relative atomic mass and find out the

facts.

² Select necessary item from the common table and construct solar models of atoms allocated

to you.

² Be prepared to present constructions and findings to the class.

20


"Looking at an atom with an exploratory eye"

Annex 1.2.3

Do you know that all matter solids, liquids and gases found in your environment is formed by

110 elements getting grouped together in different ways ?

Each of these elements are formed from building units called atoms.Although it is not possible to

look at an Atom or its interior using the naked eye, the way the scientists by performing varius

experiments have been able to learn about the structure of these is amazing. To begin with let us

find about the sub atomic particals of atoms.

Sub Atomic Particals

Copyright © 2007 National Institute of Education - Sri Lanka. All rights reserved.

Element Symbol Number of Number of Num,ber of

Electrons Protons Neutrons

Hydrogen H 1 1 --

Helium He 2 2 2

Lithium Li 3 3 4

Berelium Be 4 4 5

Boron B 5 5 6

Carbon C 6 6 6

Nitrogen N 7 7 7

Oxygen O 8 8 8

Fluorine F 9 9 10

Neon Ne 10 10 10

Sodium Na 11 11 12

Magnesium Mg 12 12 12

Aluminium Al 13 13 14

Silicon Si 14 14 14

Phosparous P 15 15 15

Sulphur S 16 16 16

Chlorine Cl 17 17 18

Argon Ar 18 18 22

Potasium K 19 19 20

Calcium Ca 20 20 20

Every element has a chemical symbol denoted by letters in the English alphabet. For easy study

it is possible to arrange the number of ptotons in the atomic nucleus of all the elements found in

the world. Now let us find out some theories about atoms.

21


Data of Elements of atomic numbers 1 - 20

Name of

Element

Chemical

Symbol

Atomoc

Number

Number of Electrons in the

shells

(Electronic configuration)

K L M N

Mass Relative

number Atomic

mass

Copyright © 2007 National Institute of Education - Sri Lanka. All rights reserved.

Hydrogen

Helium

Lithium

Beralium

Boron

Carbon

Nitrogen

Oxygen

Fluvorin

Neon

Sodium

Magnisium

Aluminium

Silicon

Phosporus

Sulphur

Clorine

Argon

Potasium

Calsium

H

He

Li

Be

B

C

N

O

F

Ne

Na

Mg

Al

Si

P

S

Cl

Ar

K

Ca

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

1

2

2

2

2

2

2

2

2

2

2

2

2

2

2

2

2

2

2

2

1

2

3

4

5

6

7

8

8

8

8

8

8

8

8

8

8

8

1

2

3

4

5

6

7

8

8

8

1

2

1

4

7

9

11

12

14

16

19

20

23

24

27

28

31

32

35

40

39

40

1

4

6'9

9

10'8

12

14

16

19

20'2

23

24'3

27

28'1

31

32'1

35'5

40

39'1

40'1

22


Atomic Number

The atomic number of an element is the number of protons in the atom of that element.(In a

neutral atom the number of protons in the nucleus is equal to the number of electrons in the

shells.)

Mass number

The mass number of an element is the sum of the protons and neutrons in the atomic nucleus

of that element,

Relative atomic Mass

You could understand that atoms are particles having a very small mass hence it is not useful

in Chemistry to use the international unit of mass,the kilogram in relation to the mass of an

atom. Hence the mass of an atom is stated as a relative value of a standard unit.It is called the

Relative atomic mass unit.

Relative atomic mass Unit = mass of

12 6

C Isotope atom

12

The relative atomic mass of an atom is the number of times the mass of that atom in relation to

the relative atomic mass unit.It could be stated as

Relative atomic mass

Relative atomic mass

= mass of an atom

atomic mass unit

= mass of an atom of an element

mass of an atom of

12 6

C isotope x 1/12

There are differences between the atoms of the same element.An example of this is the presence

of atoms of elements with same number of protons but with different number of neutrons,Such

elements where the number of protons in the atomic nucleus is the same but the number of

neutrons vary,and as a result they vary in their mass number.These are called isotopes.

A Symbol is used to identify an atom.In an atomic symbol at the top left is the mass number

and at the bottom is the atomic number(

12 6

C )

23


Annex 1.2.6

Data about some of the isotopes found in nature of some elements

Name of

element

Atomic

number

Mass

number

Symbol of

the isotope

Number of

protons

in the

nucleus

Number of

Neutrons

in the

nucleus

Number of

Electrons

in the

nucleus

Hydrogen

1

1

1

1

2

3

1

1

2

1

3

1

H

H

H

1

1

1

0

1

2

1

1

1

Helium

2

2

3

4

3

2

4

2

He

He

2

2

1

2

2

2

Lithium

3

3

6

7

6

3

7

3

Li

Li

3

3

3

4

3

3

Boron

5

5

10

11

10

5

11

5

B

B

5

5

5

6

5

5

Carbon

6

6

12

13

12

6

13

6

C

C

6

6

6

7

6

6

Nitrogen

7

7

14

15

14

7

15

7

N

N

7

7

7

8

7

7

Oxygen

8

8

8

16

17

18

16

8

17

8

18

8

O

O

O

8

8

8

8

9

10

8

8

8

Neon

10

10

10

20

22

22

20

10

21

10

22

10

Ne

Ne

Ne

10

10

10

10

11

12

10

10

10

Sulpher

16

16

16

32

33

34

32

16

33

16

34

16

S

S

S

16

16

16

16

17

18

16

16

16

24


25

17

17

19

19

19

20

20

20

20

20

20

17

17

19

19

19

20

20

20

20

20

20

35

37

39

40

41

40

42

43

44

46

48

17

17

19

19

19

20

20

20

20

20

20

18

20

20

21

22

20

22

23

24

26

28

Cl

Cl

37

17

35

17

K

K

K

41

19

40

19

39

19

Ca

Ca

Ca

Ca

Ca

Ca

48

20

46

20

44

20

43

20

42

20

40

20

Chlorine

Potasium

Calcium


Competency 1.0 ( Investigates Scientific findings about the structure

of matter and quantity.

Copyright © 2007 National Institute of Education - Sri Lanka. All rights reserved.

Competency level 1.3 ( Explain the Properties of compounds using it`s bonds.

Activity 1.3 ( Let us Investigates the Properties of compounds using it`s

bonds.

Time ( 120 minutes

Quality inputs ( ² Atomic models arranged according to instructions in

annex 1.3.1

² Two copies of instructions for exploration given in

annex 1.3.2

² Two work stations arranged according to instructions

given in annexe 1.3.3

² Two copies of the article "Chemical bonds" given in

annex 1.3.4

² Demy papers and pastels

Teaching-learning process (

Step 1.3.1 ( ² Join the atomic models accordingly with the help of the

students.

² Lead a discussion highlighting the following points.

² Bonds are formed between atoms by the electron.

² Two electrons join to form a bond between two

atoms.

² When a chemical bond is formed ,the atoms that go to

form the bond behave the following fashion.

² One atom donates an electron from its last energy

level to the other atom.

² The election donated by one atom is accepted by the

other atom.

² The positive ion formed by the donation of the eletron

and the negative ion formed by the acceptance of

electron are attracted.

² When there is no formation of ions,electron pairs are

shared between two atoms

² During the formation of bonds the atoms try to

achieve the maximum inert gas configuration.


Copyright © 2007 National Institute of Education - Sri Lanka. All rights reserved.

.

² An atom reach the maximum nobel gas configuration by

forming one or more bonds.

² Molecules are formed by atoms joining together by

chemical bonds.

² A molecules consists of two or more atoms which may be

homogeneous or heterogeneous.

² When chemical bonds form between heterogeneous atoms

compounds are formed.

² It is possible to develop the chemical equation of a com

pound by indicating the different number of atoms in a

compound molecule using the symbols of elements.

(15 mts)

Step 1.3.2 : ² Divide the class into two groups.

² Provide the groups with instruction for exploration the

article,demy papers and pastel.

² Assign the tasks and engage the groups in exploration.

² Prepare them to present their findings to the whole class.

(60 mts)

Step 1.1.3 (² Get each group to present their findings to the class.

² Give the first opportunity to the respective group to

elaborate on the presentation.

² Get the other groups to propose constructive suggestions,

² Elaborate highlighting the following points.

That,

² Atoms of elements by releasing electrons become positive

ions,and by receiving electrons become negative ions.

² The positive ions are named cations and the negative ions as

anions.

² There are ions which are formed from a single atom or from

a number of atoms.

² Oppositely charged ions are attracted together and thereby

forming ionic bonds,

² When ions get together to form a compound,the arrange

ment of ions in space is called the ionic lattice.


Copyright © 2007 National Institute of Education - Sri Lanka. All rights reserved.

² The ionic compounds have the following inherent properties.

² Solid crystalline substances made up of ions.

² Have high melting points and boiling points.

² Soluable in polar liquids.

² Conducts electricity in the fused state as well as in solution.

² A molecule is a unit formed by the union of more than one

atom of similar or dissimilar elements.

² Atoms of some elements in the solid state are arranged in a

definite pattern in space.

² The structures which are formed by the arrangement of atoms

of elements in a definite pattern are called atomic lattice.

² Some compound molecules,in the solid state,are arranged in

a definite pattern in space.

² The structures formed by the arrangement of compound

molecules in a definite pattern in space are known as molecular

lattice.

² When bonds are formed the presence of electrons are

indicated by a dottod cross.

² A single bond between two atom is indicated by a short line

in between them.

² Depending on the number of electron pair which go to from

the bond,the bonds are known as single bond,double bond or a

triple bond.

² The electron pairs in the valency orbit that do not take part in

the formation of bonds are called lone electron pairs.

² The compounds which are formed by covalent bonds have the

following properties.

² Mostly occur as neutral molecules made up of a number

of atoms.

² Occur in Solid,liquid,and gaseous state.

² Most compounds have low melting points and boiling

points.

² Some are soluble in water.

² Do not conduct electricity in aqueous solution.

² The ability of an element to combine or its combining power is

called valency.

² The number of electrons of an atom of an element that take

part in the bonds is equal to its valency.

² Ions as well as radicals have a valency.

(45 mts.)


Copyright © 2007 National Institute of Education - Sri Lanka. All rights reserved.

Criteria for Assessment and evaluation :

² Explain how ionic and covalent bonds are formed.

² Accepts the fact that there is a relationship between the chemi

cal properties of a compound and the nature of bonds.

² Investigates the physical properties of ionic and covalent

bonds.

² Use symbols as a method of presenting data.

² Make use of models to video concept.

Annexe 1.3.1

Instructons to prepare models :

Make models,as given in the diagrams,using the rigifoam sheets.

H Na Mg

Mg

O O

N

Cl


Copyright © 2007 National Institute of Education - Sri Lanka. All rights reserved.

Annexe 1.3.2

Instructions for group exploration

• You are intrested with the exploration of one of the two main groups of classifications of

chemical compounds according to the nature of their bonds.

• Covalent bonds

• Ionic bonds

• Using the article on chemical bonds,discuss about the nature of the bonds with regard to

the compounds allocated to you.

• Present by using models and symbols how the bonds are formed in the type of compounds

allocated to you giving three examples.

• Calculate the relative molecular mass of the compounds making use of the relative atomic

mass.

• Find the combining power of ions,groups of ions or atoms in the compounds provided.

• Find out whether there are other compounds which could be developed from these ions,ion

groups,or atoms.

• Investegate the solubility in water,physcial nature,heating in the air and conduction of

electricity by an aqueous solution of the compounds in your work station.

• Be prepared to present your finding to the class.

Annex 1.3.3

Instructions for setting up workstations

• Work station 1

• Sodium chloride

• Calcium hydroxide

• Copper sulphate

• Work station 2

• Glucose

• Ethanol

• Urea

• Keep the following materials in both workstations.

• water

• Two drycells

• One metre of connecting wire

• Torch bulb

• Two carbon rods

• Two beakers

• Tin cover and holder

• Burning spirit lamp


Annex 1.3.4

Chemical bonds

Ionic bonds,ionic compounds and their properties.

An ion is a positively or negatively charged atom or a cluster of atoms.

Na atom

Na + ion + e

Mg atom

Mg 2+ ion + 2e

Cl atom + e Cl - ion

S atom + 2e S 2- ion

Copyright © 2007 National Institute of Education - Sri Lanka. All rights reserved.

Examples for ions formed by a cluster of atoms are given below.These are known as ion

radicals.

Ammonium ion(NH 4

) +

Nitrate ion(NO 3

) -

Sulphate ion(SO 4

) 2-

Phosphate ion(PO 4

) 3-

In electric fields positive ions are attracted to the cathode and the negative ions to the anode.As

such if the charge in the ion is positive it is called a cation and if the charge is negative it is called

an anion. Ionic bonds is formed between positive ion formed by donating completely one or

more electron in the outer most shell of one atom to another atom,and the negative ions formed

by accepting those electrons.This is due to electro statatic attraction between the oppositely

charged ions. Consider following examples.

Ionic compounds have the following endemic properties.

• consist of ions which are oppositely charged.

• Mostly occur as crystalline solid substances.

1. The Nature of Bonding in Sodium chloride

×

×

× ×

×

× × ×

×

×

×

² ²

²² ²²

² ²² × × ²

× ²

²

²

× → × × ² ×

²

² × ² ²²

× × ²²

²² ²²

Sodium Atom Chlorine Atom Sodium ion Chloride ion

(Na) (Cl) (Na + ) (Cl - )

²

²


2' The Nature of Bonding in Lithium Oxide

Lithium Atom

Li



Oxygen Atom

× ×

×

×

O

×

Lithium Atom



Li


×

× ×


Lithium ion

Li



Oxide ion

× ×

2-

Lithium ion

+ ×


+

×

×

• O

• Li

×


× ×

3' The Nature of Bonding in Magnisium Oxide

×

×

2-

Mg

×

O


(Mg) 2+

×

O

Magnisium Oxide ^MgO&

4' The Nature of Bonding in Calcium Chloride

_

Cl

×

Cl

×

Ca

×


(Ca) 2+

×

Cl

_

Cl

Calcium Chloride ^CaCl 2

&


Ionic compounds have the following endermic properties.

• Consist of ions which are oppositly charged.

• Mostly occur as crystaline solide subtances.

• High melting points and boiling points.

• Most soluble in water.

• Conducts electricity in aqueous solutions and in the fused state.(heated and liquified)

Covalent bonds and properties of covalent compounds

A molecule is an electrically neutral cluster of atoms which is made up of more than one atom

which are of the same element or different elements by sharing electrons.

Here the electrons are shared in such a way that the atoms achieve the electronic configuration

of noble gases.

Each of these shared pair of electrons is a chemical bond.It is indicated by a single short line.

H •

+ H

H

×



×

H

Two Hydrogen Atoms

Outer most shell has one electron

Hydrogen molecule

One electron pair keep share

In order to obtain of full outer energy

level and gain the electron configuration

of the nobel gas Helium

• •

× ×

• •

× ×



Cl


+

×

Cl

×

×




Cl


×

Cl

×

×

• • • •

× × × ×

Two Chlorine atoms

Outer most shell has seven

electrons

Chlorine molecule (Cl 2

)

One electron pair keep share in orde to obtain

of full outer energy level and gain the electron

configuration of the nobel gas Argon


²

²

O ² + × O

×× →

²

O ×

²

×

O

××

² ²

×

Two Oxygen atoms Oxygen Molecule (O 2

)

Outer most shell has six electrons.

Two electrons pair keep share.In order to

obtain of full outer energy level and gain the

electron configuration of nobel gas Neon

²

²

××

²

²

×

N ² + × N × →

² N × N

²

×

×

²

Two Nitrogen atoms

Outer most shell has five electrons

×

²

²

²

×

×

Nitrogen molecule

(N 2

)

Three electron pain keep share. In order to

obtain of full outer energy level and gain the

electron configuration of nobel gas Neon

Similarly stucture of water molecule can be shown as follows.

××

²

H

× ×

²

H

×

×

×

×

²

H


×

×

×

×

²

H

Oxygen atom Two Hydrogen atoms Water molecule ^H 2

O&


Pay your attention to the nature of bonds of Carbon dioxide and Amonia molecules given

below. ××

×

×

×

×

×

××

×

×

²

²

²


×

×

×

²

×

× ×

Carbon atom Carbon dioxide molecule (CO 2

)

×

×

²

²

×

²

×

²

× ×

×

Two Oxygen atoms

²

H

×

××

×

×

N

×

Nitrogen atom

²

²

H

H


×

N

×

H H

²

×

H

²

²

Three Hydrogen atoms

Ammonia molecule (NH 3

)


Copyright © 2007 National Institute of Education - Sri Lanka. All rights reserved.

The number of short lines drawn between the atoms shows the number of electron pairs

shared by the atoms.If the number of shared electron pairs is one,it called a single bond,if two

a double bond and if three, a triple bond. When the bonds are indicated by short lines the

electrons in the outermost shell which do not take part in bonds should also be indicated.

•• •• •• ••

H-H • Cl Cl O O •

• N N

•• •• •• ••


Covalent compounds have the following endemic properties.

•Mostly occur as small neutral molecules made up of few atoms.

•Occur in the solid,liquid and gaseous states.

•Most compounds have low melting points and boiling points.

•Some are soluble in water.

•Do not conduct electricity in aqueous solution.

Ionic lattice

The structure which indicates how the ions are arranged in a three dimensional space in a

chemical compound is called an ionic lattice.In the case of some elements the atoms are

arranged in a lattice.The structure of arrangement of atoms which are joined by covalence

bond is a three dimentional space is called an atomic lattice.

Eg1: Carbon-Graphite

Eg. NaCl ionic lattice


Every atom of carbon in graphite exit in a two dimensional

lattice by combining with three other carbon atom by single

bonds.Graphite blocks are formed by arranging these layers

one on top of another.The bonds between these layers are

weak and as a result one layer could slide over another easily.

Because of this graphite is used as a lubricant.

Eg2: Carbon-diamond

Copyright © 2007 National Institute of Education - Sri Lanka. All rights reserved.

Molecular lattice

some elements which occur as molecules or molecules of compounds sometimes are arranged

in space as a lattice.The structure which indicates the three dimensional arrangement of

molecules in space is called amolecular lattice.

Eg. Moleculer lattice of Silicon dioxide ( SiO 2

)

In Diamond every carbon atom forms four covalent bonds

with four other carbon atoms and as indicated in the diagram

in the form of a three dimensional lattice.Diamond has a high

value because it is the hardest substance in nature and is also

because it is a very rare and attractive mineral. Making use

of the fact that it is the hardest substance it is used to make

delicate parts of instruments which should not be wasted

and in glass cutting.


The combining power or the combining ability of an element known its' valency. The following

table indicates the valency of some elements and ion radials.

Valency

1 2 3

Lithium Li +

Magnesium Mg 2+

Aluminium Al 3+

Metal

Sodium Na +

Potassium K +

Calcium Ca 2+

Copper(II) Cu 2+

Iron(III) Fe 3+

Silver Ag +

Zinc Zn 2+

Copper^I& Cu +

Irona(II) Fe 2+

Lead Pb 2+

Barium Ba 2+

Hydrogen H +

Oxide O 2-

Nitride N 3-

Non

Metal

Fluoride F -

Chloride Cl -

Sulphide S 2-

Bromide Br -

Hydride H -

Iron

Radical

Hydroxide OH -

-

Nitrate NO 3

+

Ammoinum NH 4

-

Hydrogen HCO 3

Carbonate

Carbonate

2-

CO 3

Sulphate

2-

SO 4

Phosphate PO 4

3-

The chemical formula of a compound is by using symbols and the number of different atoms in

the molecule of the compound,

H 2

In the hydrogen molecule there are two hydrogen atoms.

Cl 2

In the chlorine molecule there are two chlorine atoms

NH 3

In the Ammonia molecule, there is one Nitrogen atom and three hydrogen atoms.

H 2

SO 4

In Sulphuric acid molecule, two atoms of hydrogen, one atom of sulpher and four

atoms of Oxigen

When a compound if formed by atoms of two elements they must be constructed in such a

way so as to balance the valencies of atom


Copyright © 2007 National Institute of Education - Sri Lanka. All rights reserved.

Example-

1. Sodium chioride is made of univalent Na + ion and univalent Cl - ion

combining .Formula - NaCl

2. Magnesium chloride is made by bivalent Mg 2+ ion and two

univalent Cl - ions.-Formula- MgCl 2

3. Magnesium oxide is made up of bivalent Mg 2+ ion and bi valent

oxygen O 2- ion combining formula -MgO

4. Sodium hydroxide is formed by univalent Na + combining with uni

valent(OH) - ion.Formula-NaOH

5. Sodium carbonate is formed by two ions of univalent Na+ and

bivalent (CO 3

) 2- . Formula Na 2

CO 3

6. Copper sulphate is formed by bivalent Cu 2+ combining with

bivalent (SO 4

) 2- ion, Formula CuSO 4

7. Aluminium sulphate is formed by two atoms of trivalent Al 3+ ion

2-

combining with three ions of bivalent (SO 4

)ions

. Formula Al 2

(SO 4

) 3

8. Water molecule is formed by two atoms of univalent hydrogen

combining with one atom of bivalent oxygen. Formula H 2

O

9. To develop the above formulae the valency of atoms,ions or ion

radicals of simple compounds could be made use of,seewhether it

is possible to draw a connection between the formula of the

compound and the valency of atom or ion radicals using the

above example.


Competency

1.0( Investigates the Scientific findings about the

structure of matter and quantity.

Copyright © 2007 National Institute of Education - Sri Lanka. All rights reserved.

Competency level 1.4 Use mole to quantify elements and Compounds.

Activity 1.4 ( Let us quantify matter.

Time ( 120 minutes

Quality inputs ( ² An enlarged copy of data table given in annexe 1.4.1

² Two copies of instructions for exploration given in

annexe 1.4.2

² Demy papers and pastels

Teaching-learning process (

Step 1.4.1 ( ² Asks from the students that if the mass of a two rupee coin is

8g what is the easiest way to seperate ten thousand of those

coins.

² Exhibit the data table to the class.

² Direct students to get together in group of two and calcu

late the number of atoms in a relative mass of an atom,in

grammes,or the number of molecule in grammes.

² Lead a discussion highlighting the following facts.

² The number of atoms in a relative atomic mass of an

element in grammes has been calculated to be about

6.022x10 23

² The number of molecules in a relative molecular mass

of a compound in grammes has to be calculated to be

about 6.022x10 23

² The number of atoms in a relative atomic mass of an

element in grammes or the number of the molecules

in a relative molecular mass of a compound in grammes

is 6.022x10 23

² A mole of a substance is 6.022x10 23 fundamental enti

ties of that substance

6.022x10 23f fundamental units which make up matter,the

atom,molecule,ion,subatomic particles is called a mole

of that matter.

² Mole is an international unit which measure the quantity

of matters.


Copyright © 2007 National Institute of Education - Sri Lanka. All rights reserved.

² The number of fundamental units included in a mole is

constant,this constant called the Avogardo Constant(L

or N A

)

( ² Avogadro constant is N A

= 6.022 x 10 23 mol -1

² The mass of a mole of substance is called the molecu

lar mass of that substance.(M)

Eg.In a mole of carbon atom mass of 6.022x10 23

carbon atom is 12g

Hence molecular mass of carbon is 12gmol -1

Eg.In a mole of water there are 6.022x10 23 molecules

of water.Its` mass is 18g.Hence the molecular mass

of water is 18gmol -1

² The value of the mass of an element when stated in

grammes is equal to the relative atomic mass of that

element.

² The value of the mass of a mole of compound when

stated in grammes is the relative molecular mass of that

compound.

² When it is required to weight substance of small mass

like atoms,molecules ,it is easy to weight the required

amount of that substance.

² When we want to seperate a quantity of substance,the

knowledge of the molecular mass of that substance is

useful.

(15 minutes)

Step 1.4.2 ( ² Divide the class into three groups.

² Provide each group with copies of the article instruc

tions for exploration,demy paper and marker pens.

² Assign tasks and engage groups in exploration.

² Prepare them to present their findings to the class.

(60 minutes)

Step 1.4.3 ² Get groups to present their findings to the class.

² Give the first opportunity to the respective group to elaborate on the


presentation.

² Get the other groups to propose Constructive suggestions.

² Summerize highlighting the following points.

² If the mass of an element/compound(m),and the number of

moles of Atoms/molecules(n)

The relationship is n=m/M

² The mass of a quantity of moles(n)of an element /compound

is(m),we get the following relationship.

m = Mxn

² The mass of an (N) number of atoms of an element is(m),

The relationship we get is

m = MxN/N A

² The relationship we get when a mass(m) of an element/com

pound contain(N) number of molecules is

N = (m/M)xN A

² When (n) number of moles of an element/compound contain(N)

number molecules the relationship is

N = nxN A

² The relationship of mass of an atom /molecule(m 0

) is shown by

m 0

= M/N A

.

² When it is required to get a specific quantity of matter and

quantitative calculations in chemistry,the above relation

ships are useful.

(45 mts)

Criteria for assessment and Evaluation

² Define the terms mole,Avogadro constant and molecular mass.

² Accepts that in chemistry when there is a need to quantify elements/compounds.

² Develop relationsship associated with quantitative of elements and compounds.

² Shows relationalships using equation.

² Investigates the accuracy of a relationaship.


Annex 1.4.1

Data Table

Element

Mass of

a atom/g

Relative

Atomic

Mass

Compound Mass of

a compound

molecule/g

Relative

Molecular

Mass

Copyright © 2007 National Institute of Education - Sri Lanka. All rights reserved.

H

C

N

O

Instructions for group exploration

² Focus your attention to the type of matter given below assigned to your group.

² Element

² Compound

1.66 x 10 -24 1

1.99 x 10 -23 12

2.32 x 10 -23 14

2.66 x 10 -23 16

Annex 1.4.2

² Develop suitable expressions to quantify the matter assigned to you.It is possible to include

Avogardo constant N A

whereever suitable.

H 2

O

CH 4

NH 3

CO 2

2.99 x 10 -23

2.65 x 10 -23

2.82 x 10 -23

7.31 x 10 -23 18

16

17

44

² m 0

mass of an electron of element/ mass of a molecule of a compound whose

molecular mass is M

² mass m of an element/compound contains n moles of atoms/molecules whose

molecular mass is M

² mass m of an element/compound contains N number of atoms/molecules

whose molecular mass is M

² In n moles of an element/ compound contained N atoms/ molecules whose

molecular mass is M

² By making use of the relationships appropriately, select the problems and final solutions to

the matter assigned to you.

² The molecular mass of carbon is 12gmol -1 .Find the number of moles in 10g of carbon.

² The releative atomic mass of oxygen is 16.Find the number of atoms in 10g of oxygen.


² The molecular mass of nitrogen is 14gmol -1 .Find the mass of an atom of nitrogen.

² The molecular mass of hydrogen is 1g mol -1 . Find the number of hydrogen atoms in 0.1

mol of hydrogen.

² The molecular mass of carbondioxide is 44gmol-1.Find the number of atoms in 20g of

carbon dioxide.

² The relative molecular of Methane is 16gmol-1.Find the number of moles in 0.2g of

methane.

² The molecular mass of water is 18g mol -1 .Find the number of moles in 20g of water.

² Be prepared to present your findings to the class.

Copyright © 2007 National Institute of Education - Sri Lanka. All rights reserved.


Competency 2.0 ( Investigates Periodic patterns in properties of

elements.

Copyright © 2007 National Institute of Education - Sri Lanka. All rights reserved.

Competency level 2.1 ( Investigates properties of elements change according

to the atomic number.

Activity 2.1 ( Let us investigate the changing patterns in properties of

matter..

Time ( 120 minutes

Quality inputs ( ² Four copies of instructions for exploration given in annex

2.1.1

² Four copies of "Physical properties of matter" table given

in annex 2.1.2

² Graph papers demy papers and pastel

Teaching learning process (

Step 2.1.1 ( ² Display the class an enlarged figure of the diagram

below.

² Get some of the student to complete the pattern given

above.

² Conduct a discussion highlighting the following points•

² There is a pattern in the change in direction of the

arrow.

² After a definite number of squares we come across an

arrow which is directed in a similar direction.

² Patterns which occur again and agian at definite

intervals are known as periodic pattern

. ² Awareness of patterns simplify science education.

(15 mts)

I

Step 2.1.2 ( ² Divide the class into three groups.

² Provide the groups with exploration

instructions,table,graph papers,demy papers and pastel.

)

² Assign the tasks and engage the groups in exploration.

² Prepare them to present their findings to the class.

(60 minutes)

45


Copyright © 2007 National Institute of Education - Sri Lanka. All rights reserved.

Step 2.1.3 ( ² Get each group to present their findings to the class.

² Give the first opportunity to the respective group to

elaborate on the presentation.

² Get the other groups to propose constructive sugges

tions,

² Elaborate highlighting the following points.

That,

² C and Si elements are at the top graph on of melting

points

² He,Ne,Ar elements are at the bottom of the graph on

melting points.

² According to the graph the variation in temperature of

liquifactors shows a periodic pattern.

² Element C and Si are at the top of the graph boiling

points.

² Elements He,Ne,Ar are at the bottom of the graph

giving boiling points

² According to the graph the variation in boiling points

shows a periodic pattern.

² Elements B and Al are at the top of the graph

givining density

. ² Elements H,N,Na and K are at the bottom of the

graph giving density.

² According to the graph indicating variation in density

shows a periodic pattern.

² The volume occupied by a molecular mass of an

element when expressed in cubic centimetres it is

called the atomic volume.

² In the graph giving the atomic volumes of

elements,He,Na, and K elements are placed at the

top.

² In the graph giving the atomic volumes of elements B

and Al elements are placed at the bottom.

² According to the graph, variation in atomic volumes

of elements shows a periodic pattern.

² Properties of elements is a periodic function of the

atomic number.

(45 mts)

46


Criteria for assessment and evaluation

² Explain the variation in pattern of temperature of liquifaction/boiling point/density/

atomic volume, of elements against the atomic number.

² Appreciates that there is a periodic variation shown by the atomic number against

properties of elements.

² Draw graphs to show variation of properties of elements.

² Explatins a graph.

² Makes educational activities easy by understanding patterns.

Copyright © 2007 National Institute of Education - Sri Lanka. All rights reserved.

Annex 2.1.1

Instructions for group exploration

² Your group is expected to investigate how one of the properties given below vary according

to the Atomic number.

² Melting point of elements

² Boiling points of elements

² Density of elements

² Atomic volume of elements

² Using the table given draw a graph with Atomic number against the respective property.

² Enlarge the graph developed by you, and draw on a demy paper.

² Be prepared to present your findings to the whole class

47


Annex 2.1.2

Physical Properties of Elements

Elements

Atomic

number

Melting

point/ 0 C

Boiling

point/ 0 C

Density

at 20 0 C

g cm -3

Atomic

volume

cm 3 mol -1

H

1

-259

-253

0.071

14.1

He

2

-270

-268.9

0.125

31.8

Li

3

180

1330

0.53

13.1

Be

4

1283

3000

11.84

4.9

B

5

2030

2550

2.34

4.3

C

6

3600

4800

2.25

5.4

N

7

-210

-196

0.81

17.3

O

8

-218

-183

1.14

14.0

F

9

-220

-188

1.15

17.1

Ne

10

-249

-245

1.20

16.8

Na

11

97.8

890

0.97

23.7

Mg

12

651

1100

1.74

14.0

Al

13

660

2500

2.70

10.0

Si

14

1410

2400

2.42

16.6

P

15

44

280

2.34

14.1

S

16

113

445

2.07

15.5

Cl

17

-103

-35

2.00

18.7

Ar

18

-189

-186

1.66

24.0

K

19

63

766

0.87

45.0

Ca

20

840

1500

1.55

26.0

(Source : Book of Data for Teachers of Chemistry / 1989, NIE)

48


Competency 2.0 ( Investigates Periodic patterns in properties of

elements.

Competency level 2.2( Investigates the realtionship between the position in

periodic table and the properties of elements.

Activity 2.2 ( Let us return to the periodic table.

Copyright © 2007 National Institute of Education - Sri Lanka. All rights reserved.

Time ( 120 minutes

Quality inputs ( ² Provide a large elaborate periodic table in annexe 2.2.1

² Four copies of Instructions for exploration given in

annexe 2.2.2

² Four copies of "Diversity in Physical and chemical

properties" of elements in annexe 2.2.3

² Graph papers demy papers and pastel

Teaching learning process (

Step 2.2.1 ( ² Exhibit the periodic table to the class.

² Direct the students to observe the data indicated by

symbols,numbers and colours.

² Conduct a discussion highlighting the following point.

²The elements are grouped in the periodic table for

easy study of element.

²The transverse rows of the periodic table are called

periods,they numbered as 1,2,3,4 etc.The vertical

rows are called groups and they are numbered

I,II,III,IV,V,VI,VII,VIII or O

²The elements are grouped in the periodic table as

periods and groups ,according to a foundation based

on argument.

(15 mts)

Step 2.2.2 ( ² Divide the class into three groups.

² Provide the groups with instructions for exploration

graph papers,demy papers and pastel.

² Assign the tasks and engage the groups in exploration.

² Prepare them to present their findings to the whole class.

(60 minutes)

49


Step 2.2.3 ( ² Get each group to present their findings to the class.

² Give the first opportunity to the respective group to

elaborate on the presentation.

² Get the other groups to propose constructive sugges

tions,

² Elaborate highlighting the following points.

That,

² The number of electrons in the outermost shell of an

atom of the element is equal to the number of the

group to which the element belongs.

² The number of shells containing electrons is equal to

the number of the period to which the element

belongs.

² Most elements to the left hand side of the periodic

table are found in the solid state.

² The elements at the top on the right hand side of the

periodic table are in the gaseous state.

² The elements in the left hand side of the periodic table

are mostly metals and when you go forward along a

period non metals are found.

² When you move down along a group containing

metals there are elements which show strong metallic

properties.

² The density of elements from groups I to IV in 2 and

3 periods,increase regularly ,but from V to O it

decrease regularly.

² When we move forward along 2 and 3 periods,the

atomic volume decrease up to group III,gradually

increase thereafter.

² When we move forward along 2 and 3 periods,from

group I to IV the melting point and the boiling point

increase where as groups V,VI,VII and O the

elements have very low melting point and boiling

points.

² When we move forward along a period,the

oxides,chlorids and hydrides changes from ionic

to covalent types.

(45 mts)

50


Criteria for assessment and evaluation

² Explain varying patterns of properties of elements when moving forwards along periods

and down along groups.

² Appreciate that the elements are classified in the periodic table for easy study of properties

of elements.

² Discovers connection between the position of element in the periodic table and the proper

ties of the element.

² Understands natural patterns.

² Use graphs to present data meaningfully when it is suitable.

51


Annex 2.2.1

Periodic Table

Copyright © 2007 National Institute of Education - Sri Lanka. All rights reserved.

.

52


Copyright © 2007 National Institute of Education - Sri Lanka. All rights reserved.

Annexe2.2.2

Instructions for group exploration

² Your group is assigned to study the relationship between the place in the periodic table and

its properties in one of the following.

² moving forward along the second period

² moving forward along the third period

² moving down along groups I,II,III,IV

² moving down along groups V,VI,VII,O

² By using the periodic table and the table privided understand the patterns in the following.

² Number of electrons in the outer most shell

² Metallic,non metallic,physical state

² Density

² Atomic volume

² Melting point/Boiling point

² Acidicity-Basicity of oxides/Hydrides

²Be prepared to present your findings to the class using graphs whenever required.

53


Annex 2.2.3

Diversity of Chemical and Physical Properties of elements

Elements Atomic

Number

Electronic

Config.

Metalic/

Non

Metalic

Nature of

Oxide

Density

gcm -3

Atomic

Volume

cm -3

mol

melting

point 0 C Boiling

point 0 C

H

1

1

0.071

14.1

-259

-253

He

2

2

0.125

31.8

-270

-268.9

Copyright © 2007 National Institute of Education - Sri Lanka. All rights reserved.

Li

Be

B

C

N

O

F

Ne

Na

Mg

Al

Si

P

S

Cl

Ar

K

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

2, 1

2, 2

2, 3

2, 4

2, 5

2, 6

2, 7

2, 8

2, 8, 1

2, 8, 2

2, 8, 3

2, 8, 4

2, 8, 5

2, 8, 6

2, 8, 7

2, 8, 8

2, 8, 8, 1

0.53

11.84

2.34

2.25

0.81

1.14

1.15

1.20

0.97

1.74

2.70

2.42

2.34

2.07

2.00

1.66

0.87

13.1

4.9

4.3

5.4

17.3

14.0

17.1

16.8

23.7

14.0

10.0

16.6

14.1

15.5

18.7

24.0

45.0

180

1283

2030

3600

-210

-218

-220

-249

97.8

651

660

1410

44

113

-103

-189

63

1330

3000

2550

4800

-196

-183

-188

-245

890

1100

2500

2400

280

445

-35

-186

766

Ca

20

2, 8, 8, 2

1.55

26.0

840

1500

Ga

31

2, 8, 18, 3

5.90

11.8

30

2237

Ge

32

2, 8, 18, 4

5.46

13.3

937

2837

As

33

2, 8, 18, 5

5.72

13.1

613

sublimation

Se

34

2, 8, 18, 6

4.80

16.5

220

685

Br

35

2, 8, 18, 7

3.12

25.6

-7.2

58.5

Kr

36

2, 8, 18, 8

3.00

32.3

-157

-153

54


Competency 3.0 ( Use chemical reactions appropriatily to fulfil

requirments in life.

Competency level 3.1 Classify chemical recations

Activity 3.1 ( Let us understand about types of reactions.

.

Copyright © 2007 National Institute of Education - Sri Lanka. All rights reserved.

Time ( 120 minutes

Quality inputs ( ² !0 cm 3 of concentrated nitric acid

² A copper wire of 30 cm length,half of which is made into

a coil

² Boiling tube

² Four work station prepared according to instructions

given in annex 3.1.1

² Four copies of instructions for group exploration given in

annexe 3.1.2

² Demy paper and pastel

Teaching learning process (

Step 3.1.1 . (

² Introduce the coiled end of the copper wire into the

boiling tube containing concentrated HNO 3

and display to

the class.

² Direct the students to observe what happens

² Conduct a discussion highlighting the following points.

² When conc HNO 3

reacts with Cu metal given

coloured Cu(NO 3

) 2

solution is formed and reddish

brown coloured NO 2

is given out.

55


² During chemical reactions ,simple substances are

converted to complex substances or complex

substances are converted to simple substances.

² The chemical reactions could be grouped according

to the nature of the reaction.

(15 mts.)

Copyright © 2007 National Institute of Education - Sri Lanka. All rights reserved.

Step 3.1.2 ( ² Divide the class into four groups.

² Provide the groups with instructions for exploration

graph papers,demy papers and pastel.

² Assign the tasks and engage the groups in exploration.

² Prepare them to present their findings to the whole class.

(60 minutes)

Step 3.1.3 ( ² Get each group to present their findings to the class.

² Give the first opportunity to the respective group to

elaborate on the presentation.

² Get the other groups to propose constructive sugges

tions,

² Elaborate highlighting the following points.

That,

² Elements Iron and sulphur combine to form sulphide.

² Magnesium and oxygen combine to form magnesium

oxide.

² When a different compound is formed when an ele

ment-element,or element-compound or compoundcompound

combine is known as a combination

reaction.

² When potassium permanganate is heated it dissociates

into simple compounds.

² When hydrogen peroxide is heated it dissociates into

simple compounds.

² When a compound dissociates into simple compounds

or to elements and simple compounds,it is called a

dissociation reaction.

² Metal magnesium,reacts with copper sulphate releasing

Cu metal forming Magnesium sulphate.

² Zinc metal reacts with dilute sulphuric acid liberating H 2

gas and form zinc sulphate.

56


² When an element displace another element in a compound

and takes its place and form another compound it is

called single replacement reaction.

² When calcium chloride react with sodium carbonate

calcium carbonate and sodium chloride is formed.

² When ferrous sulphate reacts with sodium hydroxide

,ferrous hydroxide and sodium sulphate is formed.

² When an element or a radical of a compound,reacts with

an element or a radical of another compound undergo an

exchange reaction it is known as a doubel replacement

reaction.

(60 mts)

Criteria for assessment and evaluation

² Classify chemical reaction and describe using examples.

² Apperciates that chemical changes during a reaction can be made use of to classify chemical

change.

² Demonstrate chemical reaction.

² Data given using symbols are made use of gainfully.

² Demonstrate skills in using equipment.

Annexe3.1.1

Instructions to set up work stations

Set up four work stations by keeping the following materials.label materials and equipments.

Work station 01

² Iron filings 3.5 g

² Sulphur powder 1.5g

² Boiling tubes 01

² Holders 01

² Sprit lamp 01

² Piece of Magnesium ribbon 01

Work station 02

² KMnO 4

4g

² H 2

O 2

solution 20 cm 3

² Boiling tubes 02

² Holders 01

² Spirit lamp 01

² Dry ekle pieces 02

57


Copyright © 2007 National Institute of Education - Sri Lanka. All rights reserved.

Work station 03

Work station 04

² 2 cm length of clean magnesium ribbon

² Solution of Cuso 4

(2g of Cuso 4

in 100cm 3 of water)

² Zinc pieces 1g

² Dilute H 2

SO 4

acid 10 cm 3

² Two test tubes

² Test tube rack

² CaCl 2

solution (CaCl 2

0.5g in 10 cm 3 of water)

² Na 2

CO 3

solution (Na 2

CO 3

0.5g in 10 cm 3 of water)

² FeSO 4

solution(FeSO 4

0.5g in 10 cm 3 of water)

² NaOH solution (NaOH 0.5g in 10 cm 3 of water)

² Four test tubes

² Test tube rack

Instructions for group exploration

² Concentrate your attention on the two reactions assigned to your group.

² Heating iron filings with sulphur/burn magnesium in air

² Heating of Potassium permanganate/Heating of Hydrogen peroxide

² Reaction between magnesium and Copper sulphate/Reaction between zinc and dilute

sulphuric acid

² Reaction between Calcium Chloride and Sodium Carbonate/Reaction between

ferrous sulphate and Sodium hydroxide

² Familiarize yourself with the materials kept at the respective work station.

² Conduct the reaction and record your observations.

² Write down the equations for the chemical reactions.

² Using prefered symbols,develop a common equation to represent both reactions.

² Be prepared to present your findings to the class.

58


Competency 3.0 :Use chemical reactions appropriatily to fulfil

requirments in life.

Competency level 3.2 : Investigates interaction between matter and electricity

Copyright © 2007 National Institute of Education - Sri Lanka. All rights reserved.

Activity 3.2 : Let us find out connection betwen matter and electricity

.

Time : 120 minutes

Quality inputs : • copper and zink sheet of 2 cm x 5 cm size.

• Fruit (Lime,Orange,Apple) or potatoe yam

• LED bulb

• Three copies of instructions group exploration given in

annex 3.2.1

• Common table prepaired according to instructions in

annex 3.2.2

• Demy paper and pastel

Teaching learning process : • Insert the zink and copper sheets into the fruit

(Lime,Orenge,Apple) or potato yam, so that they are

close together but not touching. Connect the LED bulb

amd demostrate its' glow.

• Conduct a discussion highlighting the following.

• That electricity is produced when subtances in the

fruit/potato yam interacts with the metals.

• There is an inter connection between matter and

electricity

(15 mts.)

Step 3.2.1 • Divide the class into three groups.

• Provide the groups with instructions for exploration,

demy paper and pastels.

• assign the tasks and engage the groups in exploration.

• Prepare them to present their findings to the whole class

(60 mts.)

Step 3.2.2 : • Get the group to present their findings to the class.

• Give the first opportunity for elaboration to the respec

tive group which made the presentation.

• Get the other groups to propose constructive suggestions

59


• Elaborate highlighting the following points.

• The following observations were noted when Copper

(II) Chloride solution was electrolyse.

• Copper was deposited on the electrode connected to

the negative terminal of the battery.

Cu 2+ (aq)

+ 2e Cu (s)

• Chlorine gas was liberated at the electrode connected to the

positive terminal of the battery.

2Cl - (aq)

+ 2e Cl 2 (g)

+ 2e

• When a moist litmus paper was exposed to Chlorine gas it

decolourised.

• The green colour of the solution grsduslly redused.

• temperature of the system increased.

)

( 45 mts)

• With lighting of the bulb, flow of current through the electrolyte

was confirmed.

• It is possible to change matter by supplying electricity from

outside.

• Effecting a chemical change at the electrodes by passing a

current through an ionic solution (electrolyte) is known as

electrolysis.

• During electroplating of the iron plate the following observa

tions were made.

• Copper was deposited as a thin film on the iron plate.

Cu 2+ (aq)

+ 2e Cu (s)

• Copper plate gradually dissolved.

Cu(s) Cu2+ (aq) + 2e

• Colour of the solution did not change

• Level of the solution increased.

• The depositing of a metal on a surface is known as Electroplating.

• By electroplating a surface gets a metallic finish and protection.

• When bulb is connected between Copper and Zink plates

immersed in dilute sulphuric acid,

• The bulb ignited.

• Zink plate gradually dissolved.

• Gas bubbles got collected on the Copper plate.

• When bulb is connected between Copper and Zink plates

immersed in dilute sulphuric acid, an electric current is produced

• A set up where an electric current is produced, associated with

a chemical change is known as an electric cell.

• Electric currrent could be obtained from dry cells and batteries.

60


• Removal of electrons from an atom, an ion or a radical is

Oxcidation.

• Intake of electron from an atom, an ion or a radical is Reduction.

• Electrode where Oxidation is taking place is known as Anode.

• Electrode where reduction is taken place is known as Cathode.

(45 mts)

Criteria for assesment and evaluation

Copyright © 2007 National Institute of Education - Sri Lanka. All rights reserved.

• Explain about electric cells, electrolysis and electroplating.

• Appreciates that it is possible to enhance daily living using the

relationship between matter and electricity.

• Investigates the relationship between matter and electricity.

• Prepair a diagram with a set up selecting the materials.

• Use demostration effectively for communication.

Instruction for group exploration

• Your group is assigned to study the interaction between matter and electricity using one of

the following.

• Chemical cells.

• Electrolysis

• Electroplating

• Study the diagram in the respective precincts , select the necessary materials to prepare the

set up from the commen table.

• Make the setup.

• .Observe the following and report on the set up relevant to you

• Changes that take place at the electrodes.

• Changes in the solution.

• Is there a change in temperature during the reaction?

• Did the bulb ignit?

• What are the possible ions in the solution provide to you?

• Be prepared to present your findings to the class along with a

demostration.

61


Keeping diagrams in the work stations

Annex 3.2.2

Work Station 1

+

4 V_

+ _

Bulb

Carbon Electrodes

CuCl 2

Aqeous Solution

Work Station 2

Eletrolysis

4 V

+

_

+ _

Bulb

Cu Electrode

Fe Electrode

CuSO 4

Aqeous Solution

Work Station 3

Electroplateing

Bulb

Zn

Cu

Electrode

Electrode

Dil. H 2

SO 4

Solution

Chemical Cell

62


Annex 3.2.3

Copyright © 2007 National Institute of Education - Sri Lanka. All rights reserved.

Materials and apperatus on common table

• Carbon Electrodes 02

• Copper electrodes 02

• Zinc electrodes 01

• 2 cm x 5 cm Iron plate (surface cleaned )

• Dry Cells 06

• 1.5 V Bulbs 03

• Thermometers 03

• 100 cm 3 Beaker 03

• 0.5 mol dm -3 CuCl 2

aqeous solution 100 cm 3

• 0.1 mol dm -3 Dil. H 2

SO 4

Solution 100 cm 3

• 0.1 mol dm -3 CuSO 4

Solution 100 cm 3

• Litmus papers

• Connecting wires

α

α

±±

.

63


Competency 3.0 ( Use chemical changes suitably to fulfil necessities

in life

Competency level 3.3 ( Investigates reaction patterns of pure metals.

Activity 3.3 ( Let us explore the reactivity of metals.

Copyright © 2007 National Institute of Education - Sri Lanka. All rights reserved.

Time ( 120 minutes

Quality inputs ( ² Piece of Sodium metal,knife and a basin of water

² Four work stations prepared according to instrutions

given in annex 3.3.1

² Four copies of instructions for group exploration given in

annex 3.3.2

² Demy papers and pastel

Teaching learning process (

Step 3.3.1 ( ² Direct the students to observe how a cut surface a

freshly cut piece of sodium change with time.

² Demonstrate to the class the reaction between sodium

and water by putting a piece of sodium into a basin of

water.

² Conduct a discussion highlighting the following points.

² Sodium is a pure metal.

² When a freshly cut surface of sodium metal is

exposed to air for a short time it looses its shine.

² Sodium metal reacted vigorously with cold water.

² It is possible for the reactivity metals could differ

from metal to metal.

(15 mts)

Step 3.3.2 ( ² Divide the class into four groups.

² Provide the groups with exploration

instructions,table,demy papers and pastel.

² Assign the tasks and engage the groups in exploration.

² Prepare them to present their findings to the class.

(60 mts)

Step 3.3.3 ( ² Get each group to present their findings to the class.

² Give the first opportunity to the respective group to

elaborate on the presentation.


Copyright © 2007 National Institute of Education - Sri Lanka. All rights reserved.

² Get the other groups to propose constructive sugges

tions,

² Elaborate highlighting the following points.

² When Mg,Al,Zn,Fe and Cu metals are kept in the air

for a short time there is no observable change.

² When Mg is heated it burns with a glowing flame.

² When Al, Zn, Fe and Cu are heated in air they loose

their shine.

² When Mg, Al,Zn,Fe, and Cu are heated in air it re

acts with the oxygen in the air and forms the oxide of

he metal.

Eg: 2Mg(s)+O 2

(g) → 2MgO(s)

² Mg metals reacts very slowly with cold water releas

ing gas bubbles.

² Al,Zn,Fe and Cu do not show any observable

reaction with cold water ,in a short time.

² Mg reacts some what vigorously with hot water

releasing gas bubbles.

² Al and Zn reacts very slowly with hot water releasing

gas bubbles.

² Fe and Cu does not show any visible reaction with

hot water,in a short time.

² When Mg,Al and Zn reacts with water,hydrogen gas

is released forming the hydroxide of the metal.

Eg Mg(s)+2H 2

O(l) → Mg(OH) 2

(aq)+H 2

(g)

² Mg,Al,Zn and Fe reacts with dilute acids releasing

gas bubbles.

Eg Mg(s)+2HCl(aq) → MgCl 2(

aq)+H 2

(g)

² Cu does not react with dilute acids.

² Due high reactivity of Na ,it is dangerous to heat the

metal in air or react it with acids/Hot water.

² A metal whose reactivity is high could displace a

metal whose reactivity is less from an aqueous

solution of it.

Eg: Fe(s)+Cu 2+ (aq) →

Fe 2+ (aq)+Cu(s)

² It is possible to arrange the metals in their order of

reactivity in a series.

Cu


.

² The metal series arranged according to decreasing

reactivity,is known as the activity series.

² Scientists have developed the activity series, by

including metals explored and in addition the other

metals as follows.

Na

K

Ca

Copyright © 2007 National Institute of Education - Sri Lanka. All rights reserved.

Na

Mg

Al

Zn

Fe

Cu

Au

Exploring

metal

Mg

Al

Zn

Fe

Cu

Sn

Pb

Hg

Ag

Pt

Au

Build up

activity

series

Introduced

metal

² Activity series is useful when studying about metals.


Criteria for assessment and evaluation

² Explanes how the activity of two metals could be compaired

² Accepts that sequential arrangement of metals in the series developed, and the activity series

in agrement.

² Compair the activity of two matals experimentaly.

² Come to conclutions basing observations

² Able to observe the effect of a factor by controlling the

variables.

Copyright © 2007 National Institute of Education - Sri Lanka. All rights reserved.

Instructions for setting up of work stations

² Set up four work stations for activities.

² Provide the four work stations with the following materials.

² Boiling tube

² Two test tubes

² Test tube stand

² Test tube holder

² Bunsen burner

² Pieces of sandpaper

² Small Scissor

² Cold water and hot water

² Two test tube containing 10 cm 3 of CuSO 4

solution

² Provide the work stations with one of the following

² Six pieces each of Mg and Al

² Six pieces each of Al and Zn

² Six pieces each of Zn and Fe

² Six pieces each of Fe and Cu

(Each of these metals must be of the same size as a 2 cm length of Mg)

Annex 3.3.1


Instructions for group exploration

Copyright © 2007 National Institute of Education - Sri Lanka. All rights reserved.

² For exploration you are provided with one of the following metal groups.

² Mg-Al

² Al-Zn

² Zn-Fe

² Fe-Cu

² Observe the reactivity of the metals seperately with the follwing

(cut the metal into small pieces when required)

² Air

² Cold water

² Hot water

²Dilute Hydrochloric acid

²CuSO 4

Solution

² From your observations compare the reactivity of the two metals.

² Develop with a discussion a series in the ascending order of reactivity of the two metals

provided,along with sodium and gold.

² Be prepared to present your findings to the class.


Competency 3.0 ( Use chemical changes suitably to fulfil necessities

in life

Competency level 3.4 ( Use suitable methods for extraction of metals

Activity 3.4 ( Let us find about methods for extraction of metals.

Copyright © 2007 National Institute of Education - Sri Lanka. All rights reserved.

Time ( 120 minutes

Quality inputs ( ² Piece of Lead,Lead monoxide,blow pipe,charcoal block

and bunsen burner.

² Two copies of instructions for group exploration given in

annex 3.4.1

² Two copies of article on "extraction of metals" in annex

3.4.2

² Demy papers and pastel

Teaching learning process (

Step 3.4.1 ( ² Show the class a piece and lead monoxide

² Ask from the student about the possibility of turning

lead oxide to lead.

² Put some lead monoxide into a hole in the piece of

charcoal block,and direct the bunsen flame to the hole by

blowing through the blow pipe.

² Allow students to observe the change.

² Lead a discussion high lighting the follwing points.

² Lead is formed by the dissociation of lead monoxide

by heat.

² During extraction of some metals thermal methods

are used.

² Other methods too are used for extraction of metals

² When selecting a suitable method for extraction it is

important to consider the form in which it is available

in nature and the chemical activity of the metal

(15 mts).

69


Step 3.4.2 ( ² Divide the class into two groups.

² Provide the groups with the article on instructions for

exploration ,demy papers and pastel

Copyright © 2007 National Institute of Education - Sri Lanka. All rights reserved.

² Assign the tasks and engage the groups in exploration.

² Prepare them to present their findings to the class.

(60 mts)

Step 3.4.3 ( ² Get each group to present their findings to the class.

² Give the first opportunity to the respective group to

elaborate on the presentation.

² Get the other groups to propose constructive sugges

tions,

² Summrize highlighting the following points.

² The following points are agreeable for metals at the

top of the activity series.

² Reaction is very high

² Because they react fast with air and water they are

kept either immersed in paraffin oil or imeared with a

protective covering.

² They are available in nature as chloride of the metal.

² The metal is extracted mainly electrolysing the fused

metal chloride.

² The following points are valid for metals at the middle

of the activity series.

² Shows medium range of reactivity.

² Mainly available in nature ,as oxide of the metal

² Carbonate of the metal or Sulphide of the metal.

² Metal is extracted by thermal dissociation of

oxides,Sulphides or Carbonates.

² The following points are valid for metals at the bottom

of the activity series.

² Reactivity is very low.

² Available in nature as pure metals,not as com

pounds.

² Extraction is by separating the metal from the soil

particles by physical means.

(45 mts)

70


Annex 3.4.1

Criteria for assessment and evâlution

² Explain the basic methods of extraction of metals.

² Appreciates that there is a connection between the reactivity of the metal,from in which it is

available in nature ,and method of extraction

² Correlate the place occupied by a certain metal in the activity series and its properties.

² Gather facts by using reacting materials.

² Present the facts collected in a way understood by the others.

Annex 3.4.1

Copyright © 2007 National Institute of Education - Sri Lanka. All rights reserved.

Instructions for Group exploration

² You are expected to make a study of a metal group belonging to the activity series given

below.

K

Na

² Metals with high reactivity Ca

Mg

Al

² Metals with middle rate

of reactivity

² Metals with low reactivity

Zn

Fe

Sn

Pb

Cu

Hg

Ag

Pt

Au

² Using the artical supplied to you,gather data according to the headings given below,about the

metal group assigned to you

² Availability in nature

² Method of extraction

² How it is stored

² Gather data about the metal gold under the headings given above,and compare with metals

assigned to you.

² Be prepared to present your findings to the class.

71


Metal extraction

Annex 3.4.2

Ores in which the metal with present as the metal chloride

Ore

Sodium Chloride

Potassium Chloride

Main constituents

in the Ore

NaCl

KCl

The metal extracted

Sodium

Potassium

Copyright © 2007 National Institute of Education - Sri Lanka. All rights reserved.

Magnesium Chloride

Calcium Chloride

MgCl 2

CaCl 2

Ores in which the metal is present metal oxide

Types of Ore

Haematite

Magnatite

Limonite

Boxite

Cuprite

Tinstons

Much constituents

in the Ore

Fe 2

O 3

Fe 3

O 4

Fe 2

O.2H 2

O

A l2

O 3

.2H 2

O

Cu 2

O 3

SnO 2

Ores in which the metalis present as the metal carbonate

Magnisium

Calcium

The metal extractor

Iron

Iron

Iron

Aluminium

Copper

Tin

Types of Ore

Callamine

Limestone

Malkite

Aturaite

Magnasite

Main constitutent

in the Ore

ZnCO 3

CaCO 3

CuCO 3

.Cu(OH) 2

2CuCO 3

.Cu(OH) 2

MgCO 3

The metal extractor

Zinc

Calcium

Copper

Copper

Magnisium

72


Ores in which the metal is present as metal sulphide

Types of Ore

Copper Pyrites

Zincblent

Galena

Zinabar

Main constituents

in the Ore

CuFeS 2

ZnS

PbS

HgS

Metal extractor

Copper

Zinc

Lead

Mercury

Copyright © 2007 National Institute of Education - Sri Lanka. All rights reserved.

Methods of Extraction

Electrolysis of Fused compound

Metal

Sodium

The compound that is electrolysed to extract the metal and

the chemical reaction that take place

Available in nature as Sodium Chloride. In the Downs process

Sodium Chloride id fused and electrolysed. For it to liquify easily it is

mixed with Calcium Chloride.

NaCl → Na + + Cl -


CaCl 2

Ca 2+ + 2Cl -

² At the anode Cl 2

if formed.

² At the cathode Na metal is formed.

(the diagrames mention under Sodium extraction)



Potassium

Calcium

Available in nature as KCl. The metal is obtained by

electrolysing the fused Chloride.

Available as CaCO 3

in nature. By adding Hydrochloric acid to

this, CaCl 2

is formed. Fused CaCl 2

is electrolysed in Graphaite

crucible.

² Metallic Calcium is deposited on the cathode.

² Chlorine is evolved at the Anode.

73


Metal

The compound that is electrolysed to extracts the metal

and chemical reactions take place

Magnesium

Magnesium Chloride is present in nature as Carnalite in sold deposites;

Fused Carnalite is electrolysed in Iron vessels. Here mostly MgCl 2

undergo electrolysis.

Aluminium

Aluminiumis present naturally as Boxite. (Al 2

O 3

.2H 2

O) This is purified

and fused , then it is desolve in purified and fused Cryolite (3NaF.AlF 3

)

It is electrolysed.

Copyright © 2007 National Institute of Education - Sri Lanka. All rights reserved.

2. Reduction of the Ore with Carbon or Carbon Monoxide

Metal

Iron

Zinc

Reactions and the way reduction is performed

Th Ore Hematite (Fe 2

O 3

) is roasted , and the oxide is obtained without

any vapourising material, These oxide is heated in a blast furnance

reduced by Carbon monoxide.

Fe 2

O 3

+ 3CO → 2Fe + 3CO 2

(The diagram is mention under Iron extraction)

Zinc blend (ZnS) or Calomine (ZnCO 3

) is roasted in air

convert to the oxide

2ZnS + 3O 2 → 2ZnO + 2 SO 2

this oxide is mixed

with Coke powder and reduced.

ZnO + C

Zn + CO

Tin

The Tinstone (SnO 2

) Ore is roasted in air and later toasted with

Carbon.

SnO 2

+ 2C

Sn + 2CO

Galena (PbS) first converted to Leadoxide.

Lead

2PbS + 3O 2

2PbO + 2SO 2

Later , Lead is obtained as in the reaction given below.

PbO + C Pb + CO

PbO + CO Pb + CO 2

74


Extraction of Sodium

Sodium is extrcted by Electrolysing fused Sodium chloride. To reduced the melting point of

Sodium Chloride to 600 0 C, it is mixed with CaCl 2

. The fused solution is electrolysed by using

the Down's cell.

Chlorine gas

Copyright © 2007 National Institute of Education - Sri Lanka. All rights reserved.

Fused Sodium metal

Fused Sodium Chloride

and Calcium

Chloride mixture.

Down's cell

Fused Sodium metal

Cylindrical steel

cathode

Steel diaphragm to

avoide the reaction of

Sodium and Chlorine.

Carbon (Graphite)

anode

The cathode is made of steel and the anode is of Graphite. During electrolysis the following

reactions take place at the electrodes.

At cathode

Na + + e Na

At anode 2Cl - Cl2 + 2e

75


Iron Extraction

The Ore that is frequently used is hematite which contains Iron (111)

Moisture,Sulphur.Arsenic are present in the ore as impurities.To remove these the ore is

roasted in air.Hematite is then mixed coke. Coke is a type of coal which produced more heat.

For this the Ore is mixed with Limestone. The heat required is supplied by coke. Limestones

remove sand in the Iron. This reaction taken place in a blast furnace.

Copyright © 2007 National Institute of Education - Sri Lanka. All rights reserved.

Iron Ore,

Coke and

Limestones

gas impurities

Hot air in

Liquid Iron out

gas impurities

Hot air in

Blast Furnace

The diagram given above show a blast furnace. The mixture is introduced to the furnace at the

top. The temperature in this furnace is more than 1500 0 C. The chemical reaction taking place

could be shown step by step as shown below.

1. The Oxygen in the air that enter the furnace with coke react to form Carbon dioxide.

C + O 2

CO 2

2. This CO 2

reacts further with Coke and forms CO gas.

CO 2

+ C 2 CO

3. The CO gas reacts with Iron (III) Oxide and form Iron.

Fe 2

O 3

+ 3CO 2Fe + 3CO 2

4. In addition to CO Carbon too reacts with Iron Oxide to form Iron.

Fe 2

O 3

+ 3C 2Fe + 3CO

76


Extraction of Gold

Metals Gold, Platinum, Silver and Mercury usually do not react with other elements chemically

to form compounds. These metals are called inactive metals and they are found in nature as the

elements.

But it is mixed with gravel, sand and other soil particals. The has to be seperated from the

impurities. Gold could be obtained from Quart Ore, river sand or gravel as small peices. Here

the most simple mathode to extract the Gold is to sieve the river sand and gravel. Seeving is a

process where gravitational mathodes dependent on dencity. During seeving heavy gold metal

gets collected at the bottom of the vessel and the gravel and sand gets washed out by the mining

wates. Directing the water spout at the gold containes and gold could be extracted.

Copyright © 2007 National Institute of Education - Sri Lanka. All rights reserved.

Another mathod is quarts is powdred and mixed with water , is passed over amalgamated copper

electrodes. In this process gold is dissolved at the surface of the plate. Later the Mercury is

bistilled.

A piece of rock which contains gold

77


Competency 3.0 : Use chemical change suitable to fulfil necessity of life

Competency

Level 3.5 : Control the rate of chemical reaction

Activity 3.5 : Let us investigate about the factors affecting the rate of

chemical reaction.

Time : 210 mts.

Copyright © 2007 National Institute of Education - Sri Lanka. All rights reserved.

Quality Inputs : • Spakle, Sandalwood stic and a box of matches

• Four copies of the two page artical on instructions for

exploration given in annex 3.5.1

• Four work station arranged according to instrution given

in annex 3.5.2

• Demy papers and pastels

Teaching Learning Process

Step 3.5.1 • Ignit the Sparkle, Sandalwood stic at the same time and

direct the students to observe.

• Discuss about the students observations.

• Lead a discussion highlighting the following points.

• When Sparkle and Sandalwood stic were ignited the

chemicals present in them burn.

• The rate of burning of Spakle is greater than the rate of

burning of Sandalwood stic.

• There are different factors which could affect the rate

of a reaction.

• The rate of a chemical reaction could be decided by the

time taken to decrease a certain quantity of reactants or

the production of a certain quantity of the product.

(15 mts.)

Step 3.5.2 : • Divide the class into four groups.

• Provide the group with instrutions for exploration, demy

pastels.

• Assign the tasks and engage the groups in exploration.

• Prepare them to present their findings to the class.

(60 mts. )


123456789

123456789

123456789

123456789

123456789

123456789

123456789

123456789

123456789

123456789

123456789

123456789

123456789

123456789

123456789

123456789

123456789

123456789

Copyright © 2007 National Institute of Education - Sri Lanka. All rights reserved.

Step 3.5.3 : • get each group to present their findings to the class.

• Give the first opportunity to the respective groups to

elaborate on the presentation.

• get the other groups to propose contructive suggestions.

• Summerize highlighting the following points.

• In the experiment it is necessary to keep the factors

constant other than the factor which we are experimenting

• In a reactionwhere a gaseous product is obtained to

determine the rate of reaction the volume of gas liberated

at a definite time interval or the time taken to

liberate equal volums of the gas could be measured.

• In the reaction between Magnesium and Acid euqal

weights of cleaned pieces of Magnesium ribbon must

be used.

• When the effect of temperature is determined, equal

sizes of clean iron nails, equal volums of KMnO 4

,

H 2

SO 4

acidmust be used and the time taken for the

violet colour to disappear must be compaired.

• When acids are used , precautionary measures for safty

must be taken.

• When considering the effect of temperature the difference

in the temperatures of the solutions must be about

15 0 C .

• When Calcium Carbonate (Marble Chips) are used,

powder or crystals of equal weight must be taken.

• For the Hydrogen peroxide dissociation reaction a

recent production of Hydrogen Peroxide must be used.

• In the experiment to find the effect of concentration on

rate of reaction the set up given below could be used.

Mg ribbon

Rubber

Bung

Glass Tube

H 2

HCl

(i)

(ii) (iii) (iv)


• In the experiment to determine the effect of temperature

on rate of reaction the experiment to be set up as given

below

Cleaned

Iron nail

KMnO 4

$H 2

SO 4

Solution

Copyright © 2007 National Institute of Education - Sri Lanka. All rights reserved.

(i)

At room temperature At 60 0 C temperature

• In the experiment to determine the effect of physical

nature of the reactants the experiment could be set up

as given below.

HCl

CaCO 3

• In the experiment to determine the effect of catalysts the

experiment could be set up as given below

(ii)

O 2

CO 2

Syringe

H 2

O 2

MnO 2

or Sand

(45 mts.)


Step 3.5.4 : • Set up earlier groups and direct them to work stations

• Assign the tasks and engage the groups in exploration.

• Prepare them to present their findings to the whole class.

(45 mts.)

Copyright © 2007 National Institute of Education - Sri Lanka. All rights reserved.

Step 3.5.5 : • Get groups to present their findings to the class.

• Give the first opportunity for elaboration to respective

groupwhich made the presentation

• Get other groups to propose contructive suggestions.

• summerize highlighting the following points.

• When Mg reacts with HCl with different concentrations,

the time taken to liberate a constant volume of gas de

creased with tthe increase in concentration.

• concentration affects the rate of reaction.

• when Fe reacts with Acidic KMnO 4

of same concentration,

with increase in temperature the time taken for the violet

colour in the solution to disappear was less.

• Temperarure affects the rate of reaction.

• The time taken for a definit volume of CO 2

to liberate when

powdered CaCo 3

is less than when the CaCo 3

is in the

cryslline form.\

• Physical nature of the reactants affect the rate of reaction.

• When MnO 2

is used, the dissociation of H 2

O 2

increases.

• MnO 2

acts as a catalyst during dissociation of H2O 2

• Catalyst affects the rate of reaction.

• A catalyst is a constituent itself undergoing a chemical

change or a decrease in weight.

• When gases reacts if there is an increase of presure the

frequency of gas molecules colliding increase and as a

result the rate of reaction increase.

• It is possoble to control the rate of a reaction as required

by controlling concentration, temperarure, physical nature,

catalysts and pressure.

• Controlling the rate of chemical reactions it is possible to

increase the productivity and efficieancy in day to activities

of chemical production.

Criteria for assesment and evaluation

(45 mts.)

• Name and explane the factors affecting the rate of a

reaction.

• Accepts the fact that by controlling the factors affecting the

rate of a reaction, the reaction rate could be kept at an

optimum level.


• Set up experiments and test the factors affecting the rate of

chemical changes.

• Conducts activities according to a plan.

• Develope self creations by considering the opinions of

others.

Annex 3.5.1

Instructions for group explorations - handout 1

• Your group is assigned to find the effect of the following factors on the rate of a chemical

reaction.

• Concentration

• Temperature

• Physical state

• catalyst

• Device an experiment to find the effect of the factor using the instrutions and other materials

provides in the work station.

• Be prepaired to present your plan to the class

Instructions for group explorations - handout 2

• Focus your attention to any proposed changes to the plan you submitted.

• Set up apperatus according to plan and carry out experiment.

• Report your observations.

• Get ready to present your findings to class.

Annex 3.5.2

Instrutions to set up work stations

Work station I - Concentration

• 3 pieces of Mg ribbon ( 3 cm )

• Sand papers

• 3 Boiling tubes

• Glass tubing ( about 10 cm)

• Rubber stopper

• HCl solution of 2 mol dm -3 , 1 mol dm -3 , 0.5 mol dm -3 concentrations

• Stop watch

Work station II - Temperature

• 2 Fe nails

• KMnO 4

solution ( 0.1 mol dm -3 )

• H 2

SO 4

acid solution (1 mol dm -3 )

• Water trough containing hot water.

• Two boiling tubes.

• Measuring cylinder.

• Sand paper

• Thermometer

• Stop watch


Work station III - Physical nature

• Equal weight of Calcium Carbonate crystals and powder.

• Dilute HCl solution

• Conical flask

• Delivery tube

• Rubber stopper

• Thistle Funnel

• Measuring cylinder

• Water trough

• Beehive shelf

• Stop watch

Copyright © 2007 National Institute of Education - Sri Lanka. All rights reserved.

Work station IV - Catalyst

• Conical flask

• Delivery tube

• Hydrogen Peroxide solution

• Manganese dioxide/ Sand

• Syringe ( glass)

• Measuring cylinder

• Rubber stopper


Competency 3.0 : Use chemical changes suitable to fulfil necessities of life

Competency level 3.6 :

Take steps to prevent metal corrosion

Activity 3.6 : Let us find ways to conserve metal by minimizing corrosion.

Time : 120 mts.

Copyright © 2007 National Institute of Education - Sri Lanka. All rights reserved.

Quality inputs : • Potassium fericyanide and Phenolpthalein

• Small quantity of freshly prepared FeSO 4

and NaOH

• 3 copies of artical on instructions for exploration in annex

3.6.1

• 3 work stations arranged according to instructions in annex

3.6.2

• Demy paper and pastel

Teaching learning

process : • Inquire about their precious knowledge on rusting of iron.

• Add to the freshly prepared FeSO4 solution a few drop of

potassium ferricyanide and a few drop of phenolpthalien to

NaOH solution and show the students.

• Lead a discussion highlighting the following points.

• Rusting is due to water and Oxygen reacting with Iron

• Acids and salts increase rusting where as bases retard

rusting.

• Initial reactions during rusting could be given as follows.

Fs (s)

Fe 2+ + 2e (Oxidation)

(aq)

2H 2

O (l)

+ O 2(g)

+ 4e 4OH - (reduction)

(aq)

• When Potassium fericyanide is added to a solution of Fe 2+

solution there is a deep blue colours.

• Potassium ferricyanide could be used as an indicator to

detect Fe 2+ ions in a medium.

• When Phenolphthalein is added to a solution containing

(OH) - there is a pink colour.

• Phenolphthalein could be used as an indicator to detect

(OH) - ions in a medium.

(15 mts.)

Step 3.6.2 : • Divide the class into four groups.

• Provide the groups with instrutiions for exploration, demy

papers and pastels.

• Assign the tasks and engage the groups in exploration.

• Prepare them to present their findings to the whole class

(60 mts)


123456

123456

123456

123456

1234567

1234567

1234567

1234567

1234567

1234567

1234567

1234567

1234567

1234567

Step 3.6.3 : • Get the group to present their findings to the class.

• Give the first oppotunity for elaboration to the respective

group which made the presentation

• Get the other groups to propose constructive suggestions.

• Summerize highlighting the following points.

• Where the medium turned blue, Iron corrode and forms

Fe ++

• Where the medium turned pink, OH - are formed.

Pink Pink

Mg

1234567

1234567

Zn Cu Pb

1234567

1234567

1234567

Copyright © 2007 National Institute of Education - Sri Lanka. All rights reserved.

Pink

Blue

• Where the Iron is in contact with metals above Iron the

following occur

• Iron does not corrode.

• The matal which has the higher reactivity acts as the

anode and undergo corrosion due to Oxidation.

• Iron acts as the cathode.

• At the iron nail which acts as the cathode there is a pink

colour due to the production of (OH) - iron.

• These areas are called ‘cathode areas’

• When the metal which has a higher reactivity acts as the

anode and sacrifies itself and prevents iron from rusting,

it is called cathode protection.

eg. applying zink on iron surface. (galvanizing)

• When any two metals in the activity series are in contact

with one another, the metal which has a higher reactivity

corrode protecting the meatal of lower of reactivity

metal which corrodes is called the sacrificing metal.

• When metals which are below iron in the activity series

are in contact with iron the following take place.

• Iron corrodes vigorously.

• Iron acts as the anode and forms Fe 2+ by oxidation.

• The blue coloured area near iron nail, which acts as the

anode is called the anode area.

• When a metal is coated to prevent it from coming in

contact with factors which are necessary for corrosion, and

preventing iron from becoming the anode, it is called anose

protection.

eg. coating Iron surface with Sn, paint, grease.


• It is possible to keep the ions formed at the cathode and

the anode by using a jelly medium instead of a liquid

medium in the places where they are formed in a experi

ments where rusting of iron is considered as anelectro

chemical change.

• The process of rusting of Iron could be explained by the

following reactions.

Fe(s) Fe 2+ + 2e

(aq)

2H 2

O (l)

+ O 2 (g)

+ 4e

4(OH) - (aq)

Copyright © 2007 National Institute of Education - Sri Lanka. All rights reserved.

Criteria for assesment and evalution

Fe(OH) 2 (aq)

+ O 2(g)

Fe 2

O 3

.H 2

O (s)

• Iron rust is a hydrate Ferric oxide, having a reddish brown

color, a number of water molecules in it vary. As such the

compound is indicated as follows.

Fe 2

O 3

.xH 2

O(s)

(45 mts.)

• Explain anodic protection and cathodic protection which

prevents rusting of Iron.

• Appreciate that metallic corrosion could be controlled.

• Experiments how metals with different reactivity affect corrosion

of Iron

• Arrive at inferences from observation.

• Use demostrations as the occasion demands.


12345678901234

12345678901234

12345678901234

12345678901234

12345678901234

12345678901234

12345678901234

12345678901234

Instruction for group exploration Annex 3.6.3

• Your group is assigned to study about rusting of Iron nails

under one of the following conditions.

• When in contact with Mg and when in contact with Sn

• When in contact with Al and when in contact with Pb

• When in contact with Zn and when in contact with Cu

• prepair a set up to investigate the rusting of Iron nails when the

two metals are kept in a jelly medium (Prearation of a jelly

medium is given below)

• Device a suitable control experiment.

Petri dish

Copyright © 2007 National Institute of Education - Sri Lanka. All rights reserved.

Iron nail

Metal piece

Jelly medium

• Forecast what observations you expect to get after one day.

• Take down your observation on the following day.

• Arrive at conclutions about rusting of Iron, considering the

place occupied by the metals subjected to the experiment.

• discuss why it is necessary to use a jelly medium instead of an

aquaious solution, and the jelly medium should not be allowed

to have air bubbles.

• Explain the following phenomena scientifically basing your

conclusion.

• when an Iron bucket coated with Zn (Galvanized) gets

scrached rusting is controlled and could be used for a long

time.

• When food container made of Iron sheet and coated with

Sn get scrached it undergoes rusting very rapidly.


How to prepare the jelly medium

Dissolve a small quantity of NaCl in 250 cm 3 of water, add 5g of Agar and while stirring well

boil for about 10 mts. Once the mixture is viscous add 2 cm 3 of phenolphthalein, take away

the beaker from the burner stir and when it is some what cool add 1 cm3 of Potacium

ferricyanide and stir further. Before it gets solidified add to petri dishes with Iron nails and

allowed to cool. (See that air bubbles do not get into the jelly). It ispossible to use poedered

sago instead of jelly.

Instrution for preparation of work stations.

Annex 3.6.2

Copyright © 2007 National Institute of Education - Sri Lanka. All rights reserved.

• Keep the following materials and prepare 4 work stations.

• work station - 1 - Three Iron nails (7 cm) , sand paper, 3 petri dishes, Mg and Sn

metal strips 1 piece (size 0.5 cm x 5 cm)

• work station - 2 - Three Iron nails (7 cm), sand paper, 3 petri dishes, Al and Pb

metal strips 1 piece (size 0.5 cm x 5 cm)

• work station - 3 - Three Iron nails (7 cm), sand paper, 3 petri dishes, Zn and Cu

metal strips 1 piece (size 0.5 cm x 5 cm)

• Keep at each work station materials required to prepare a jelly medium.


Competency 3.0 : Use chemical changes suitably to fulfil necessities of life

Comptency level 3.7 :

Control burning as appropriate to the occasion

Activity 3.7 : Let us look, find out about burning

Time : 120 mts.

Copyright © 2007 National Institute of Education - Sri Lanka. All rights reserved.

Quality inputs : • Three lengh wise folded half sheet papers, so that they are

easily ignited.

• Three copies of instrutions for exploration article given in

annex 3.7.1

• Three work stations arranged according to the instructions

given in annex 3.7.2

• Demy paper and pastel

Teaching learning

Process :

Step 3.7.1 • Ignite one of the lengh wise folded papers and cut just below

the flame so that the flame is extinguished.

• Moistened the second paper up to two third of it with

coloured water. Ignite the paper at the dry end and display it

to the students.

• With the third paper leave the ignited end on a sheet and cover

it with an empty jam bottle, allow it to extinguish.

• Lead a discussion highlighting the following points.

• The flame extinguished as a result of the burning paper

being cut and removed ( combustible subtance isremoved)

• The flame extinguished as a result of the moistend part of

the paper did not reach the temperature required (Ignition

temperature) for it to burn.

• By covering with the jam bottle the supporter of combustion

(Oxygen) was prevented from reaching the burning

subtance.

• Three factors essential for conbustion are availability of a

combustible subtance, it should reach the ignition temperature

and the gas which is the supportes of combustion.

• A chemical reaction where a combutible subtance react

with a gaseous supporter of combustion liberating heat and

light is called combustiion.

• During combustion, the carbon and hydrogen in the com

bustible react with Oxygen in the air forming the products of

combustion.

• Paper is manufactured by plant materials which basically

contains carbon and hydrogen.


• During combustion which carbon react with Oxygen,

CO 2

is formed and when Oxygen react with hydrogen

H 2

O is formed.

(15 mts.)

Step 3.7.2 : • Devide the class into three groups

• Provide the groups with instrutions for exploration, demy

paper and pastal

• Assign the tasks and engage groups in exploration.

• Preparee them to present their findings to the whole class.

(60 mts.)

Step 3.7.3 : • Get groups to present their findings to the class.

• Give the first oppotunity for elaboration to the respective

group which made the presentation.

• Get other groups to propose construtive suggestions.

• Summerize highlighting the following points.

• when a candle is burnin, the solid wax melt and it travels

upwards along the wick and gets evaporated. This wax

vapour gets dissociate due to heat and these react with the

supporters of combustion in the surrounding air and produce

light and heat.

• In the candle flame there are three zones, which could be

observed clearly.

• The inner most zone in the non-luminous zone, it contains a

mixture of wax vapour and air.

• The temperature in the non-luminous flame is low, when

compared to the other zones.

• The zone outside the non-luminous zone is the luminous

zone, here the wax gets dissociated and Carbon monoxide

and Hydrogen gas are produced and start to form Carbon

dioxide and water.

• The tenperature in this zon is higher than the temperature in

the non-luminous zone.

• In the luminous zone, the gases containing Carbon gets

dissociated forming free Carbon particals.

• The Carbon particals get into the incandescent state and

produce the endemic yellow colour of the luminous zone

giving out light.

• The zone outside the luminous zone, at the base of the flame

a blue colour is clearly visible, but at the top it is invisible. In

this invisible zone the remaining Carbon monoxide and

Hydrogen burn.

• In the Kerosene lamp flame,two clearly visible zones, the

non-luminous and the luminous are seen.


• In the wine spirit flame, luminous flame is not visible.

Copyright © 2007 National Institute of Education - Sri Lanka. All rights reserved.

• In the bunsen burner flame, inner most is the non-luminous

zone and outer to that the dark blue and light blue zones in

sequence and outer most is the invisible zone.

• In the bunsen burner at the base the combustible subtance

is made to mix with air and then it is allowed to burn at the

top.

• A combustion reaction in which when there is a supply of

required quantity of Oxigen, the combustion substance

Carbon is completly changed to Carbon dioxide. It is called

complete combustion.

• A combustion reaction in which when there is a limited

supply of Oxigen, part of the Carbon in the combustible

subtance is converted to Carbon monoxide, it is called

parcial combustion.

• In the bunsen burner there is a supply of required quantity

of Oxigen, the fuel undergo complte combustion.

• Apart from three types considered earlier, a flame of a

higher could be got from the bunsen burner.

• When combustion takes place in a limited supply of Oxigen

the unburnt Carbon particals are given out from the flame,

which could be detected as soot by holding a ceremic brick

above the flame.

• When you hold a wire mesh transversely acroos the flame,

due to the absorption of heat by the wire mesh the flame is

not seen above the wire mesh for sometime.

• When yoy hold a glass sheet across the flame in the patch

that forms at the centre unburnt fuel is deposited.

• When you hold a fine metal piece to the outer most zone of

the flame, there is a reduction in temperature and as a result

there is partial combustion and turns luminous for a short

time.

• When you bring a flame to the vapour of an extinguished

flame soon after it was extinguished, the vapour catches

fire.

• In ovens where there are methods to control the supply of

Oxigen and fuel, it possible to obtain a flame which shows

complete combustion, with no soot but producing a higher

quantity of heat.

• When products of combustion are sent through anhydrous

Cpper sulphate there is a blue colouration which confirms

that there is production of water vapour during combustion.

• when the products are sent through lime water, the milki

ness shown confirms the production of Carbon dioxide

during combustion.

(45 mts.)


Criteria for assesment and evaluation

Instructions for group exploration

• Name the zones in the candle flame and explain their nature.

• Appreciates that combustion could be controlled depending on

its requirment.

• Observe the nature of a flame by simple experiment.

• Explane observations scientifically.

• Shows interest in the protection of one’s self, the others and

the environment.

• Your group is entrusted to find the nature of one of the flames.

• Flame of oil lamp.

• Flame of spirit lamp.

• Flame of Kerosene lamp.

• See whether the zones visible in the candle flame and in the

bunsen flame are visible in the flame provided to you.

• Engage in the following activities using the flame provided to

you.

• Holding a piece of ceremic brick to the flame horrizontally

above the flame for about 10 seconds.

• Holding a wire mesh horrizontally across the flame.

• Holding a glass slide horrizontally for about 2 sec. across

the flame.

• Introduce to the thin colourless outr zone of the flame the

end of a thin wire.

• Extinguish the flame and immediately hold the flame of an

ignited splinter close to the wick.

• Find the time required for 20 cm 3 of water in a boiling tube

to boil.

• Compare the nature of the flame provided to you with the

flames of firewood hearth, Kerosene oil cooker and a gas

oven.

• In the instances given above the fundermentel components

elements present in the fuel are Carbon and Hydrogen. The

following set up is provided to you to undestand about the

products of combustion in the flame.


• Discuss in the group the equipment to be used, procedure

to be adopted and observation expected.

• Be prepared to present your findings to the class.

Instrution setting up work station

Annex 3.7.2

Copyright © 2007 National Institute of Education - Sri Lanka. All rights reserved.

• Keep the following materials and set up three work stations.

• Piece of ceremic brick

• Copper wire guage

• Glass slide

• Piece of wire 20 cm long.

• Box of matches

• Candle stick

• In the above work stations, in the first keep coconut oil lamp in the second spirit lamp, in th

third Kerosene oil lamp.

• Display a burning bunsen burner for all the students in the class to observe.


Competency 3.0

: Use chemical changes suitably to fullfill necessities of life

Copyright © 2007 National Institute of Education - Sri Lanka. All rights reserved.

Competency Level 3.8 : Shows awareness in extinguished fires

Activity 3.8

: Prevent fire accidents'

Time : 120 mts'

Quality inputs : • Incident on ,"Hoe fire became a foe to me" in

annex 3.8.1

• Three cop[ies of instructions for group exploration given

in annex 3.8.2

• Instruction for arrangement of work stations given in

annex 3.8.3

• Artical in annex 3.8.4 on " Let us not fall prey to fire"

• Demy and pastals

Teaching- learning process :

Step 3.8.1 : • Get a student to precent the incident to class.

• Lead a discussion highlighting the following points.

• The possibility of causing fires due to unprotected

bottle lamps.

• It is possible for accidental fires to cause deaths or

bodily problems for life times.

• When a person who had caught fire to his cloths

run, the supply of Oxygen is better and as a result

could develop further.

• When clothes catch fire , it is possible to controll the

fire by wrapping the body with a gunny bag or a

thick clothe.

• Fire gets extinguished when one or more factors

shown by the fire trangle are removed.

Oxy-

Heat

Fuel

(15 mts)

94


Copyright © 2007 National Institute of Education - Sri Lanka. All rights reserved.

Step 3.8.2

Step 3.8.3

• Divide the class into three groups.

• Provide the groups with exploration instructions , the artical, demy

paper and pastel.

• Assign the tasks and engage the groups on exploration.

• Prepair them to present their findings to the class.

(60 mts)

• Get the groups to present their findings to the class.

• Give the first opportunity to the respective group to eleborate on

the presentation.

• Get other groups to prepare constructive suggestion.

• Summarize highlighting the following points.

• Fiires are grouped as follows in order to make it easy to

select the the correct fire extinguisher for the respective fire.

• A grade fires - Fires associated with Carbonic compounds

like wood, clothes, paper etc.

• B grade fires - Liquids with highly inflammable like petrolium

products, paints, wax, copra, plastic,

polithene and grease etc.

• C grade fires - All gasses which are inflammable, like

acetylene, L.P. gas, propane, butane etc.

• D grade fires - Fires from metals like Sodium, Potassium

Magnesium etc.

• It is possioble to use water fire extinguisher for A grade fires.

• Soda - Acid fore extinguisher for A grade fires.

• Foam fire extinguisher could be used for B grade fires.

• Carbon dioxide fire extinguisher especially suitable for B and C

rate fires, and when required for A grade fires.

• Halon fire extinguisher could be used for all grades of fires.

• Especially for D grade fires and sometimes for C grade fires

( Dry powder ) fire extinguisher could be used.

• Water or foam fire extinguisher are not suitable for fires which

has a electricity leakage or where there is a possibility of an

electricity leakage.

• The supply of electricity must be disconnected before any

attemp is made to extinguish a fire where there is an electricity

leakage or where there is a possibility of an electricity leakage.

• In the experimental fire extinguisher water with Carbon dioxide

under pressure comes out of the fire extinguisher where Sodium

bicarbonate and dilute Sulphuric acid reaction is used.

• In the experimental fire extinguisher where Sodium bicarbonte

and Aluminium sulphate reaction is used, the foam comes out

under pressure.

• In the experimental water fire extinguisher a jet of water under

pressure comes out.

95

(45 mts)


Critaria for assesments and evalution.

• Explane types of fires, instructions for extinguishing fires, instance where there suuitable for

use.

• Appreciates the fact that the fire extingusher must be chosen depending on the type of fire.

• Construct a simple working model of a fire extinguisher.

• Shows a tendency to protect from accidents.

• Learn from experiances of others.

How fire became a foe to me

Annex 3.8.1

I am Acvhala. From my small days I had the habit of getting up early in the morning and

helping mother. As we did not have electricity in our house we used bottle lamps. On this unfortunate

day too I got up in the morning lighted the oil lamp. When I was going to the kitchen to

ignite the hearth the bottle lamp fell erom my hand. The kerosene oil get smeared and the flame

extended. Mt clothes caught fire. When I was shoutiung and running about the flae increased

further. Fortunately I fell down. Mother came running and wrapped me with a gunny bag. Although

the flames extinguished I was unconseious. I regained consciousses at the hospital. My

hands, legs and face were burn. When I recovered I was left with a folded skin and some big

scars. Whenever I see them it gave me a great pain. I related this story to you, young sisters and

brothers, to redused my pain and also to tell you about how important it is to protect yourself

from fires.

Instruction for group exploration

Annex 3.8.2

• Draw your attention to the incident assigned to you from the following.

• To extinguish of small fire in the stationery stores of the office using the Soda Acid fire

extinguisher.

• Extinguishing a spreading fire in a fuel filling stations using a foam fire extinguisher.

• To controle a fire in carpentry shop using water fire extinguisher.

• Disscus the principal of the allocated fire extinguisher and also how the fire is extinguished.

• Arrange the set up of the fire extinguisher allocated to you by using the instruments and the

materials provided in work stations.

• Be prepared to present to thre class about the activity of the fire extinguisher you set up and

your findings you discover.

96


Instruction for setting work stations

Annex 3.8.3

Work station - I

Copyright © 2007 National Institute of Education - Sri Lanka. All rights reserved.

Bottle with a large mouth and a stopper to fit with a single hole

Small bottle without a lid

A delivery tube bend in shape L, with a jet at the end of it to fit the hole in the stopper

Dilute sulphuric acid

Consentrade solution of Sodiuim bicarbonate

Clay pot to burn a fire

Box of matches

Pieces of paper fit to burn

Piece of jute thread

The diagram

Dilute Sulphuric Acid

Sodium bicarbonete solution

Work station - II

Bottle with a large mouth and a stopper to fit with a single hole

Small bottle without a lid

A delivery tube bend in shape L, with a jet at the end of it to fit the hole in the stopper

Solution of Aluminium sulphate

Solution of Sodium bicarbonate

Clay pot to burn a fire

Box of matches

Small quantity of kerosene oil to burn

Piece of thread

The diagram

Aluminium sulpahte

solution

Sodium bicarbonete solution

97


Worl station - III

Copyright © 2007 National Institute of Education - Sri Lanka. All rights reserved.

One inch PVC pipe about 25 cm

A lid or endcap to close the end

3/4 inch wooden handle slightly longer than 25 cm

Bottom of an old slipper

Sharp knife

Some PVC gum

One inch Iron nail

Small hammer

A clay pot to burn a fire

Box of matches

Wood which ignite easily

The diagram

" Let us not fall prey to fire"

Annex 3.8.4

Fire is very essential to man but also it is distructive. Three conditions are necessary for

fire to burn. There are , a combustible subtance, heat energy required for it to burn and Oxygen.

When a fire is destructive it must immediatly extinguished. For this one or more factors given

about must be removed. Fire extinguishers are manufactured for this. All fires cannot be extinguished

from a single fire extinguisher. Because of this in order to select the best fire extinguisher

the fires are grouped.

A - grade fires

This includes fires caused by materials with contains carbonic compounds like wood, cloths,

paper etc.

B -grade fires

This includes fires caused by materials which are highly imflammable liquids, or liquids

petrolium products, paints, wax, copra, plastic, polythene, grease etc.

C - grade fires

This includes fires caused by all inflammeble gasses like Acetylene, LP gas, Propane, Butane

etc.

D - grade fires

This includes fires caused by metals like Sodium, Potassium, Magnesium etc.

98


Water fire extinguisher is used in the case of A - grade fires. A large quatity of water is blown

to and it behaves as an artificial rain and falls on the whole burning systems. As a result of the

water absorbing heat from the combustible subtaince the fire is extinguished. For small scale fires

manually controlled water fire extinguishers are used. In these water is kept at very high pressure

using Carbon dioxide or Nitrogen.

Soda - Acid fire extinguisher can be used to extinguish A - grade fires. It is arrange in a way

that the Sodium bicarbonate and dilute Sulphuric acid are kept in seperate cylinders. When these

two subtances get mixed water and Corbon dioxide are forced out at high pressure. As a result

of Carbon dioxide the fire is prevented from gettin the gas which supports combustion.

Copyright © 2007 National Institute of Education - Sri Lanka. All rights reserved.

Foam fire extinguisher is especialy designed to extinguished B - grade fires. In the foam fire

extinguisher thre is artificially prepared foam. When foam at high pressure falls on oil it floates

and prevent the combustible suntance coming in contact with the supporter of combution Oxygen.

Carbon dioxide fire extinguisher is manufactured by storing liquid Carbon dioxide at high

pressure. In case of a fire the liquid Carbon dioxide is directed on to the fire. By useing this fire

extinguisher A,B and C grde fires could be extinguished. When using this fire extinguisher it must

be used in such way to prevent accidents to the person who is using the equipment and the

people who are in the fire from inhale Carbon dioxide gas.

Halon fire extinguisher is good to extinguished all fires. It has Nitrogen gas mixed with Halon

and liquified. This gas cool the combustible substaince , and the suppoter of combution is prevented

from reaching it. A special significance of this fire extinguisher ther is no left over of

anything given out from the extinguisher.

Dry fire extinguisher the chemicals subtance used in this are Potassium bicarbonate, Sodium

bicarbonate, Ammonium phosphate and Ternary Eautetic Chloride powder. In this case when

the dry powder is directed to the fire the chemical reaction in the flame stops, prevent the combustible

subtance from reaching the ignation temperature. The superter of combution is prevented

from coming into contact with the combustible subtance, the flame is extinguished.

The fire extinguisher is specially suitable for D grade fires and sometimes for C grade fires.

99


Competency 3.0 : Use of chemical changes suitable to fulfil necessities of life

Competency level 3.9 :

Produce a gas - Examine its properties.

Time : 120 mts.

Copyright © 2007 National Institute of Education - Sri Lanka. All rights reserved.

Quality inputs : • A baloon filled with H 2

gas, according to instructions given in

annex 3.9.1. and an empty baloon.

• Three copies of article on instructions for exploration given in

annex 3.9.2

• Work stations arranged accordind to instructions given in

annex 3.9.3

• Demy papers and pastel

Teaching learning

process :

Step 3.9.1 : • Take the baloon filled with H 2

gas, to the class. (do not

mention that it contains H 2

gas)

• Give the other baloon to a student and instruct him to blow into

it so that it is of the same size as the H 2

filled baloon and tie it.

• Let the students predict as to what would happen when the

two baloons are released from hand, direct them to observe.

• Lead a discussion highlighting the following points.

• Both baloons contain the same volume of gas.

• One baloon contain H 2

gas.

• The other baloon has expired air.

• H 2

gas is less dense than normal air, as a result the baloon

went up.

• Expired air is more dense than normal air, as a result the

baloon went down.

• Different gases have different physical and chemical

properties.

(15 mts)

Step 3.9.2 : • Devide the class into three groups.

• Provide the groups with instrutions for exploration, demy and

pastal.

• Assign the tasks and engage the groups in exploration.

• Prepare them to present their findings to the class.

(60 mts.)


Copyright © 2007 National Institute of Education - Sri Lanka. All rights reserved.

Step 3.9.3 : • Get the groups to present their findings to the class.

• Give the first oppotunity to the respective groups to elaborate

on their presentation

• Get the other groups to propose contructive suggestions.

• Summerize highlighting the following points

• H 2

gas has the following properties.

• Colourless

• No smell

• Lighter than air

• Slightly soluble in water

• Doesnot change the colour of moist litmus paper

• Burn with a ‘pop’ sound when a burning splinter is

introduced

• No colour change with lime water

• It is possible to indicate the chemical reaction between Zn

and dilute HCl by the chemical equatiion given below.

Zn (s)

+ 2HCl (aq)

ZnCl 2

+ H 2(g)

• O 2

gas has the following properties.

• Colourless

• No smell

• Heavier than air

• Slightly soluble in water.

• Doesnot change the colour of moist litmus paper.

• when a glowing splinter is introduced it burns rapidly.

(suporter of combustion)

• No colour change with lime water.

• The production of O 2

gas by the dissociation of H 2

O 2

by

MnO 2

is given by the chmical equation given below.

H 2

O 2(aq)

2H 2

O (l)

+ O 2(g)

• CO 2

gas has the following propeties.

• Colourless

• No smell

• Heavier than air

• Slightly soluble in water

• Moist blue litmus paper turns pink

• Extinguish a glowing spliter

• Turns lime water milky ( when more gas is bubbled

through the solution become colourless)

• The chemical reaction which produce CO 2

by reacting

CaCO 3

with dilute HCl is given by the equation given

below.

CaCO 3(s)

+ 2HCl (aq)

CaCl 2(aq)

+ CO 2(g)

+ H 2

O (l)

(60 mts.)


Criteria for assesment and evaluation

• State the properties of O 2

, H 2

and CO 2

gases.

• Appreciates that gases have varying properties.

• Tests the properties of gases.

• Prepare a set up illustrated by a diagram

• confirms identity by properties.

Annex 3.9.1

Getting a baloon filled with H 2

Copyright © 2007 National Institute of Education - Sri Lanka. All rights reserved.

Tub

NaOH solution

Pieces of Aluminium

Instrutions for group exploration

Baloon with H 2

Bottle

o o Water

o

Annex 3.9.2

• Your group is assigned to produce one of the gases given below and find its’ physical and

chemical properties.

• Oxygen gas

• Hydrogen gas

• Carbon dioxide gas

• Using the materials placed in the respective workstations, instruments and the diagram

prepare a set up to produce the gas assigned to you.

• Conduct the following tests to understand the properties of the gas.

• Introduce into the gas a glowing splinter with the flame extinguished

and a glowing splinter with the flame.

• Hold to the gas moistened blue and red litmus papers.

• Bubbling the gas throuh lime water.

• State your observation in each of the instances.

• Arrive at conclusions about the properties of the gas from your observations.

•Be prepared to present your findings to the class.


Annex 3.9.3

Instructions to set up work stations

• Prepare three workstations and provide with materials necessary to set up an experiment as

given in the illustration below.

Thistle funnel

Delivery tube

Copyright © 2007 National Institute of Education - Sri Lanka. All rights reserved.

Conical flask

• Provide each workstation with a illustration of the experiment, two test tubes, lime water,

Red and Blue litmus papers, splinters and box of matches.

Work station - 01

Water

Gas jar

Trough

Beehive shelf

• MnO 2



H 2

O 2

2H 2

O 2 (aq)

Mno 2

2H 2

O (l)

+ O 2(g)

(In a display board)

Work station - 02

• Zn turnings

• Dilute HCl acid

• Zn (s)

+ 2HCl (aq)

ZnCl 2(aq)

+ H 2(g)

(in a display board)


Work station - 03

• CaCO 3

• Dilute HCl acid

• CaCO 3(s)

+ 2HCl (aq)

CaCl 2(aq)

+ CO 2(g)

+ H 2

O (l)

(In a display board)

Copyright © 2007 National Institute of Education - Sri Lanka. All rights reserved.


Competency 3.0 : Use chemicals reaction appropriately to fulfil requirments

in life.

Competency level 3.10:

Investigates experimentally changes in heat associated with

chemical reactions.

Activity 3.10 : Let study the changes in heat associated with chemical changes.

Time : 120 mts.

Copyright © 2007 National Institute of Education - Sri Lanka. All rights reserved.

Quality input : • Two test tubes, two glass rods, 2g each of Glucose and

Sodium hydroxide

• Four work stations arranged according to the instrutions given

in annex 3.10.1

• four copies of instrutions for exploration given in annex 3.10.2

• Demy papers and pastel

Teaching - learning

process :

Step 3.10.1 : • Get two students in front of the class and give a test tube with

water and a glass rod to each.

• Provide one student with some Sodium hydroxide and the

other some Glucose and allow them to dissolve them in the

water and instruct them to report to the class any observations

about change in temperature.

• Conduct a discussion highlighting the following.

• Temperature of the solution increased when Sodium hy

droxide was dissolved in water.

• Temperarure of the solution decreased when Glucose was

dissolved in water.

• Change of heat ia associated with chemical changes.

• It is possible to calculate the change in heat by using change

in temperature of the solution.

• If the change in temperature is q , mass of the solution in m

the specific heat capacity c , the heat change is Q is

expressed by the equation,

Q = mcq

• The specific heat capacity of water is 4200 kJ 0 C -1 kg -1

• Mass of 1 cm 3 of water is 1 g,

(15 mts.)


Step 3.10.2 : • Devide the class into four groups

• Provide the groups with instrutions for exploration, demy

paper and pastel

• Assign the tasks and engage groups in exploration.

• Prepare the groups for whole class presentation.

(60 mts.)

Copyright © 2007 National Institute of Education - Sri Lanka. All rights reserved.

Step 3.10.3 : • Get the groups to present their findings to the class.

• Give the first oppotunity for elaboration to the respective group

which made the presentation.

• Get the other groups propose construtive suggestions.

• Summerize highlighting the following points.

• If heat is given out during a chemical reaction the temperature

of the reacting mixture increase.

• Reaction which liberate heat during reactions are exothermic

reactions.

• If heat is absorbed during a chemical reaction the tempera

ture of the reacting mixture decrease.

• Reactions which absorb heat during areaction are endothermic

reactions.

• In an exothermic reaction, the energy in the product is less

than that of the reactants.

• In an endothermic reaction the energy in the products is

more than more than that of the reactants.

• It is important to use quatities of reactanta which show

practically measurable temperature difference.

• In this experiment we hypothesize that,

• The entire quantity of heat associated with the reaction

was used to change the temperature of the reacting

mixure.

• Heat capacity of solutions is equal to the heat capacity

of water.

• The density of the solution is equal to the density of

water.

• Change of heat calculated in a reaction, change with the

physical nature of the product and reactants.

• Therefore when change of heat associated with a reaction is

stated it is necessary to indicate the physical state of reactants

and products.

• To observe a maximum change in temperature the loss of

heat to the enviroment must be minimized.


• Loss of heat could be minimized by conducting the experi

ment in an insulated vessel.

• To allow the reactants to mix well, the mixture should be

stirred with a stirrer/glass rod.

Criteria for assesment and evaluation

(45 mts.)

Copyright © 2007 National Institute of Education - Sri Lanka. All rights reserved.

• Explane with examples, exothermic and endothermic reactions.

• Appreciates that there ia an exchange of heat associated with chemical reactions.

• Determine experimentally the heat change associated with chemical reactions.

• Reach conclusions based on hypothesis.

• Investigates the accuracy of conclusions.

Instructions to prepare work stations

Annex 3.10.1

• Have the following set of materials in all the work stations and also specially mentioned items

in the respective work stations

• Thermometer

• Measuring cylinder

• 100 cm 3 beaker

• Stirrer or glass rod.

Work station - 01

• 50 cm 3 of HCl solution (add 8 cm 3 of concentrated HCl up to 50 cm 3 of water)

• NaOH pellets 1g

Work station - 02

• 50 cm 3 of CuSO 4

solution (dissolve 5 g of CuSO 4

salt in 50 cm 3 of water)

• Fe powder 1 g

Work station - 03

• 50 cm 3 of H 2

SO 4

( add 3 cm 3 of conc. H 2

SO 4

to 47 cm 3 of water)

• Clean Mg pieces 0.5 g

Work station - 04

• NaHCO 3

2g

• Citric acid about 50 cm 3 (dissolve 5g of Citric acid in 50 cm 3 of water)


Annex 3.10.2

Instructions for group exploration

• Draw your attention to the following chemical reactions assigned to your group

• NaOH (s)

+ HCl (aq)

NaCl (aq)

+ H 2

O (l)

• CuSO 4(aq)

+ Zn (s)

ZnSO 4(aq)

+ Cu (s)

• H 2

SO 4(aq)

+ Mg (s)

MgSO 4(aq)

+ H 2(g)

• NaHCO 3(s)

+ Citric acid (aq)

Sodium citrate (aq)

+ CO 2 (g)

+

H 2

O (l)

Copyright © 2007 National Institute of Education - Sri Lanka. All rights reserved.

• Go to your work station and device an experiment to conduct the allocated reaction to

determine the heat change.

• When handling chemical subtances be careful about the dameges to you and the others.

• Calculate the change of heat associated with a molecular mass of the solid state reactant

used.

H = 1 Na = 23 Cl = 35.5

C = 12 Mg = 24 Zn = 65

O = 16 S = 32 Cu = 63.5

• Discuss about the following points.

• Errors in the experiment.

• How to minimize errors.

• Hypothesis used in calculations.

• Be prepared for a presentation of your findings to the class.


Competency 3.0 :Use chemical changes in an appropriate way to

fulfil living requirments.

Copyright © 2007 National Institute of Education - Sri Lanka. All rights reserved.

Competency level 3.11 :Investigates how weathering of rocks help in the

formation of soil

Activity

3.11 :Let us Investigates how weathering of rocks help in the

formation of soil

Time : 120 minutes

Quality inputs : • Small pieces of granite,quartz,limestone,mica

• Three copies of instructions for exploration given in

annex 3.11.1

• Three copies of the article"Earth and rocks"

• Demy papers and pastels

Teaching-learning process :

Step 3.11.1 : • Small pieces of granite/quartz,limestone and mica are

distributed among the students and directed to observe

them.

² Inquire from the students how the substances provided

as well as similar substances are subjected to change

Conduct a discussion to highlight the following points.

That,

² According to observations ,in the piece of granite there

are black coloured and shining components are

included in different quantities.

² The piece of granite is a heterogeneous mixture.

² According to observations quartz,limestone and mica

pieces shows homogeneous nature.

² A mineral is a crystalline non carbonic substance which

is homogeneous and having a definite geometric shape

and a definite compossition.

² A heterogeneous solid mixture without a definite

compossition and a geometric shape and made up of a

number of minerals is called a rock.

² Due to physical,chemical and biological activities

minerals and rockes change into different types.

(15 minutes)


Step 3.11.2 ( ² Divide the class into three groups.

² Provide the groups with instruction for exploration the

article,demy papers and pastel.

² Assign the tasks and engage the groups in exploration.

² Prepare them to present their findings to the whole class.

(60 minutes)

Copyright © 2007 National Institute of Education - Sri Lanka. All rights reserved.

Step 3.11.3 ( ² Get each group to present their findings to the class.

² Give the first opportunity to the respective group to

elaborate on the presentation.

² Get the other groups to propose constructive sugges

tions,

² Elaborate highlighting the following points.

That,

² It is possible to distinguish three types of

rocks, igneous,Sedimentary and metamorphic

rockes.

² Igneous rocks are formed from cooling magma

coming from the interior of theEarth.

Eg. Basalt.

² Magma coming to the surface of the earth from

empting volcanoes is subjected to rapid cooling

,forms igneous rocks,which are made up of small

crystals.

Eg. Granite

² Magma which cools slowly inside the earth forms

igneous rocks with big crystals.

² Igneous rocks are very hard and there is indication to

show that they are deposited as layer or grains.

² Weathering of hard rocks result in mineral and

carbonic substances which are deposited as layers at

the bottom of reservoirs.

² When sedemented layers at the bottom are subjected

to pressure from layers above,Sedimentary rocks are

formed.

Eg. Mudstone,Conglomerate

² The Sedimentary rocks are not as hard as igneous

rocks.

Eg.Limestone


• When igneous and sedimentary rocks are subjected to

temperature,pressure and movement of the surface of

the earth,their nature changes and form metamorphic

rocks.

Eg Marble,slate

• Nature of Metamorphic rocks differs according to the

original rock from which it was formed.

• Breaking down of rocks expossed on the surface of the

earth into small parts due to physical,chemical and

biological factors is called Weatherning of rocks.

• Rocks are subjected to physical Weatherning due to

Sun,rain,wind and ice.

• Chemical Weatherning of rocks is when a rock is

subjected to a chemical change where compounds in

it are changed to simple compounds.

• Due to some activities of living beings on rocks,both

physical and chemical weatherning takes place.

• Soil is formed when sand and clay formed from

Weatherning of rocks combine with Organic matter

from plants and animals.

• Formation of rocks,and they under go weatherning and

form soil ,occur as a cycle in nature.

• Rocks in earth undergo changes from one from to

another in a cyclic movement.

(45 mts)

Criteria for assessment and Evaluation

² Explain how soil is formed from weatherning of rocks.

²Appreciates that rocks undergo changes in a cycle.

² Observe diversity in rocks..

²Collect data from sources.

² Present data in an attractive way.


Copyright © 2007 National Institute of Education - Sri Lanka. All rights reserved.

Annexe 3.11.1

Instructions for group exploration

²Your group is assigned to investigate how one type of rock is formed and how one factor

help in the weathering of rocks.

• Types of rocks according

to how it is formed

• Factors help in

weatherning of rocks

• Igneous rocks

• Chemical factors

• Metamorphic rocks

• Physical factors

• Sedmentary rocks • Human and other biological

factors

² Discuss in the group about the type of rock you are assigned to you and about the factor

that help in the weathering of rock.

² Be prepared for a creative presentation of your findings.

Earth and Rocks

Annexe 3.11.2

The day for which Anil,Upul and Namal were eagerly waiting for arrived. the three showed

a keen interest for Geology. It was for no other reason but the teacher was able to make the

classroom interesting by engaging them in various activities to arouse the interest of the

students.The trip was organised to educate them about geological resources.

Anil started the discussion by stating that"Man`s curiosity about minerals started from the

time he found that implements could be made by stones."But man used pieces of stones to

make stone implements.Rocks found nature are stones which are a combination of one or

mo

Teacher introduced his friend, geology Professor.He spoke to the three students and said,

"Our country is full of resources.out of these resources Geological resources occupy an

important place.Only a minute fraction of it could be found during this trip."

As the vehical was moving he showed a granite rock and said,early man may have made

implements from these.The granite rocks they used to make implements belong to the igneous

rocks.In Latin `Ignis`means fire.At a depth of more than 30km from the surface of the

earth,the rocks get liquietised or fused due to high temperature.This liquid is known

as`Magma`When this magma comes to the surface of the earth during volcanic eruptions,it is

called `lava`.When this lava gets cooled and solidified igneous rocks are formed.It is possible

for this lava to cool inside the earth and form igneous rocks.


In addition to granite,basalt,rhyolite and obsidian are examples for igneous rocks explained the

Professor.

At the moment the vehicle was going along a road .which was constructed recently after

cutting a hill. The Professor instructed the vehicle to be stopped. Professor said"Let us get

down from the vehicle,I will show you something". All of us walked behind the Professor.

"Can all of you see clearly the layers deposited in this cross section of the hill.Any rock which

is regularly exposed to factors and agents like high heating,high cooling,Sun,Rain,Acid rain

breaking up due to water and wind break up into small particles.This process is called

weatherning of rocks".These settle as logitudinal layers on the surface of the earth,or at the

bottom of resoviors or ocean.These layers are called sediments.If these layers are arranged

loosely they occur as gravel,sand on the sea shore and sand dunes,when futher sedimentation

on top of these,occur the weight of these layers cause the particles to get tied together and

form into rocks.These are called `sedimentary rocks`.Mudstone,Conglomerate and Siltstones

are examples for sedimentary rocks.sometime animal bones and dead bodies of micro organ

sms with calcareous(calcium carbonate) shells gets deposited for millions of years forms a

sedimentary rock.,the limestone.These deposits are seen in the Jaffna peninsula and north of

Puttalm,said i the teacher,joining the discussion."Does laterite stones (Kabok) belong to the

sedimentary rocks"asked Upul. No.we do not consider it as a sedimentary rock because it

has been found that laterite is a product of some type of largely weathered rock which include

clay.

When this discussion was going on with the Professor important was taken down in the

field note book.

The group got into the vehocle and restarted the field trip." In Marshy places and in

forests with trees, the dead animals and plant materials get collected on the soil. They under go

changes and after millions of years forms coal." questioned Anil

"Son, you raised a very good question."

When dead plant and animal matter which is carbonic matter is added to the soil it is decomposed

by microorganisms. sometimes,soft and brown coloured peat is formed from these

carbonic material after a long period. In our country peat is found in Muthurajawela.When

peat inside the earth is subjected to pressure by the layers collecting on top of it,and high

temperature,coal is formed after is long period of time.Since coal is a carbonic material it is not

grouped under as either a mineral or rock.But some scientists include coal as carbonic rocks

under sedimentary rocks.This Process occur in lakes,resoriviors or marshy or Brakish water

having environments explained the professor.

Then upul asked that in addition to igneous rocks and Sedimentary rocks,their is metamorphic

rocks.

The high temperature and pressure inside the core of the earth or movement of the earths`

crust or chemical action with other substances and gases rocks undergo changes.


Copyright © 2007 National Institute of Education - Sri Lanka. All rights reserved.

As a result of this rocks become metamorphic rocks,explained the teacher.

During these change,the mineral composition or the texture(what you see on the surface and

what you feel when you touch it with your hand) of the rock or both could change.For example

when limestone gets metamorphed it changes to marble said the Professor.

Further examples of this are greiss,slate, and quartzite.As namal said at the begining,any type

of rock turns to liquid magma at the core of the earth.where the temperature is about 6600C.

That is correct,as magma inside the earth comes to the surface,it is called lava.Igneous rocks

are formed from magma or lava.

When we look at rocks this way I feel that there is cyclic movement among rock types.

"I wanted to explain this fact.Any type of rock on the surface of the earth undergo weathring

gets deposited as layers and form sedimentary rocks.Similarly rocks into metamorphic rocks

due high temperature,pressure and various chemical changes.The rocks in the core of the earth

gets liquified or fused and form magma and in the end form igneous rocks.In this way igneous

rocks,Sedimentary rocks,and metamorphic rocks changes from one to the other in a cycle.

This is called the rock cycle said the Professor.

Heard in another place.

This is the containing rocks.In each of these cubicles there is a different type of rock,give

the piece of rock named granite.This is not granite,it is different.This was brought from

Scotland.It is dark in colour.Its` crystals are very fine.When lava gets cooled suddenly this

high quality granite is formed. How about granite in our Country?

According to the data discovered by Scientists there is no pure granite in Sri Lanka.

But their are ancient stone pillars which are thousands of years old,we see them as if they were

built today.

Let me see the facts you wrote?The Professor started to read what they had written.

Ah.Here is the section written about weathering of rocks.

`yes`

Very good.Children this is the challange I give you.By refering to different resource material

construct an article on"the different ways of weathering of rocks".I give you two weeks from

today.There is a Valuable present for the best article and it would be published in the

Magazine.


Identify the charactors of following rocks

Sedimental

rocks

Eg. Sandtone

Copyright © 2007 National Institute of Education - Sri Lanka. All rights reserved.

Metamorphic

rocks

Eg. Schist

Igneous

rocks

Eg. Granite


T

The three friends collected data from various electronic and printed media in addition to facts

collected during the trip.not only that,they collected data from books written by Srilankan

Scientists,and also from compact discs of diffferent encyclopedias and tried to present a

resourseful artical. The Artical submitted by Upul got the frist place.It was presented in the

following manner.

Rocks break up-Soil is formed

Rocks,which is earths` heritage regularly changes due to various factors and form soil. This

Process is known as weathering of rocks.

Physical weatherning of rocks

Copyright © 2007 National Institute of Education - Sri Lanka. All rights reserved.

Due to various factors the rocks on the surface of the earth break up into small parts which is

physical weathering.Heat of the Sun,water,wind are the factors which cause physical

weathering.

a) Exporsure of rock to sunlight

The top layers of the rocks exposed to sunlight gets dried up.This is due to Sun`s heat.During

rain it gets wet.The volume of the rock increase when it is hot and decrease when it is

cold.When this process is repeated there is weathering of the rock.

wõfjkqhs

jeiafikqhs ug

yß u lrorhs

Example.Shalka gal is a sedimentary rock. It is formed by layers arranging one on top of the

other.These get regularly dried up and wet,they undergo weathering,as a result the layers of

the rock break up and ultimately from small partices.

b) Rocks dissolve in water

When rocks come in contact with water,some minerals in it gets dissolved.As a result the

structure of the rock gets weak.Because of this the rock breaks up.

When carbon dioxide is dissolved in water it is acidic,this cause weathering to take place

faster.


Copyright © 2007 National Institute of Education - Sri Lanka. All rights reserved.

c)Heating and cooling of rockes

Rocks are exposed to Sun during daytime.They undergo expansion due to Sun`s heat.At

night the rocks get coooled and as a result undergo contraction.Rocks made up of a number

of different minerals undergo weathering in this manner.Different minerals have different

coefficients of expansion.As a result the bonds between minerals in the rock become less.This

causes the surface of the rock to crack.This makes it easy for the rock to break up into small

parts.Water getting into the cracks is also a cause for weathering.

d)Sand brought by winds

When there is a heavy wind,the sand in the sea,and the rivers gets carried by it.When these

sand particles strike the rock small particles of it break off.

e)There is physical weathering due to rock particls striking one another in rivers and canals.

The pieces of rocks in rivers and canals become rounded due to parts of it getting removed.

f)Rain water could enter into the crackes in the rocks caused by various reasons.During the

winter season the water in the crackes turn to ice.The volume of ice is bigger than that of

water.As a result the crack gets bigger.This causes the rock to split up.Big rocks spilt up into

pieces in this way.

Water gets

collected

in the crackes

When

water

turn to ice

there is

crack

gets

bigger

Ice

Temperature falls

below 0 0 C

With time

the rocks

breaks up

Due to hot and cold climate

big rocks break up into small pieces.


Chemical weathering of rocks

Rocks undergo chemical weathering due to the effect of various factors on rocks.The chemical

substance cause interaction with the rocks.As a result chemical changes occur in the rocks

forming simple compounds.Here oxygen,water,and acidic substances behave a agents of

weathering.These reacton takes place very slowly.

Copyright © 2007 National Institute of Education - Sri Lanka. All rights reserved.

• The oxygen in the air,reacts with

minerals which go to form the rock,as

a result the rock undergo chemical

weathering.

For example as result of the iron

present in rocks,the rocks undergo

weathering.

Oxigen in the air cause Iron in the

rock to corrode

• Formation of new compunds due to the reaction between the rocks and water is called

hydration.Hydration too cause weatherning of rocks.

• The minerals present in the rocks,sometime undergo hydrolysis.Minerals like Sodium ,

Potassium,Calcium,Magnesium,Aluminium and Iron undergo hydrolysis.

Example:- Hydrolysis of Orthoclas rock yeild Clay.

• When Carbondioxide is dissolved in rain water a weak acid is formed.(This is called

Cabonization.) This acidic water interacts with minerals in the rock.Here the carbonate of

the mineral is formed.This also cause weathering of rocks.

Eg:- Limestone is weathered

by carbonic acid eventually

cavems are formed

• In a soil where there there is decay of carbonic material by micro organisms the

carbondioxide gas is very high.This is because of the activity of microorganisms on the

decaying carbonic material.When this carbondioxide,dissolved in water interacts with

minerals in the rocks carbonates of the minerals is formed.This cause the weathering of

rocks.

• You must have seen white,light green,light blue patches growing on rocks.These patches are

symbiotic unions between algae and fungi.They are called Lichens.Secretions emitted by

these Lichens cause weathering of rocks.

• During Lightening, the nitrogen and oxygen react forming nitric oxide and nitrous oxide.These

gases dissolve in rain water nitric acid and nitrous acid are formed.Rain water with these

acids dissolved is called acid rain.These acids,when they fall on rocks cause weathering.


Weathering of rocks by living beings

• Living beings,living the same enviroment as the rocks,contribute to the weathering of rocks.

When roots of a plant close by grow into a split in a rock caused by physical weatherning

the split gets enlarged and the rock is split up.If not,If there is a crevice formed due to

chemical weathering which is suitable for plants to grow the roots of the plants increase the

split.

Copyright © 2007 National Institute of Education - Sri Lanka. All rights reserved.

These tree rots have broken of pieces of

rocks

• Man cause weathering of rocks by breaking then up.

• When micro organisms grow on rocks the chemicals they emit cause weatherning of rocks.

• The lichens that grow on partially weathered rocks,physically or chemically,cause the

weathering of rock.

• Some animals which live associated with rocks dig up the soil around the rock.when rain

water gets collected in it cause weathering of the rock.

Eg:-Animals dig the soil around the rock.The water that is collected in these places cause

weathering of the rocks.

• When hooves and horns of animals are periodically rubbed or struck against the rocks,the

rocks get worn out.

• Reactions caused when excretons matter of animals gets collected on rocks,there is weath

ering of rocks.


Rock cycle

Igneous

(extrusive)

IGNEOUS rock is weathered

and carried to the sea by revers

Igneous

(Intrusive)

Sea

Copyright © 2007 National Institute of Education - Sri Lanka. All rights reserved.

Magma

Rock is

melted

METAMORPHIC

rock

Earth movements

squash and bury

the layers of

sedimentry rock

According to the states of cartoon nos. (1),(2) and (3) understand the above rock cycle

number (1),(2),(3).

SEDIMENTARY

rock


Tools for Extended Teaching - Learning Process

Copyright © 2007 National Institute of Education - Sri Lanka. All rights reserved.

1'0 Evaluation State ( Term 2, Tool 1

2'0 Competancy Levels covered ( 1'1" 1'2" 1'3" 1'4

3'0 Subject content covered ( ² Atom

² Sub Atomic particals

² Model for Atomic structure

² Atomic number

² Mass number

² Isotops

² Electron configuration

² Relative Atomic Mass

² Chemical bonds

² Chemical formula for Molecules

² Relative Molecular Mass

² Avogardro constance

² Mole (as a unit)

² Atomic mole

² Molecular mole

² Molecular mass

4'0 Nature of Instruments ( Presentation of literature survey

5'0 Objectives ( 1' Skill development as a finder of

new knowledge

2' To enhance the skills of reporting observations

as a scientist.

3'To involve in analyzing the reported information

using various criteria.

6'0 Instructions for implementation (

For teacher ( ² This is valid for second term science syllabus

in competency level in 1.1, 1.2, 1.3 and 1.4

Inform students to litriture survey start of the

second term.

² In this tool each student is involve in an individual

process.

² Direct the students subject content or part of

it to each student as your wish.

117


² Inform the students in advance the date at which

they have to submit the completed litreture

survey.

² Provide constructive suggestions once or twice

by examine their litreture survey before submition

Copyright © 2007 National Institute of Education - Sri Lanka. All rights reserved.

For students ( ² Use litreture review for exploration for

activities nos. 1.1, 1.2, 1.3, 1.4 relevent to

second term in your science syllabus.

² Select to find information relevent to this topic

• Magazine

• News papers

• CD s

• Internet

² Be prepair to present information you have

collected by utilizing available resources.

² Mention the sources which you get the

information finelly in the litreture reveiw.

² Submitt your litreture review to your teacher on

due date.

7.0 Format for assessment and evaluation

:

Criteria

1. Keep information accurately

2. Accuracey of information

3. Report reference sources accurately

4. Follows instructions

5. Prsents the litreture review attractively

Name of the student

Indicate Proficiency Levels as A,B,C or D

A - Excellent

B - Good

C - Average

D - Should Improve

118


Tools for Extended Teaching - Learning Process

1.0 Evaluation : Term 2, Instrument 2

2.0 Competency levels covered : 3.7 and 3.8

3.0 Subject content covered : • Action of furance

• Fire extingusher and usage

4.0 Nature of Instrument : Preparation of information leaflet

Copyright © 2007 National Institute of Education - Sri Lanka. All rights reserved.

5.0 Objectives : 1. Awearness of using combustion productivity at

day to day life.

2. To improve communication skills through informa

tion leaflet.

6.0 Instrutions for implementation :

For teachers

For students

• Encourage students to make a information leaflet.

relevent to " Action of furance and productivity

usage"or "fire extinguishers and accurate usage "

• Inform student about the source of information.

• Get student to refer the inforation leaflet issued by

various institutions.

• Prepair a information leaflet for public reguarding

" Action of furance and productivity usage" or "fire

extinguishers and accurate usage"

• Mark information which you have been collected

in infirmation leaflet concise, simple and atractive.

• Submit a prepaired infomation leaflet to your teacher

on due date.

119


7.0 Format for assessment and evaluation :

Names of Students

Criteria

Copyright © 2007 National Institute of Education - Sri Lanka. All rights reserved.

• Relevance of information

• Presentation skills

• Creativity

• Reliability of information

• Completeness of information

Indicate Proficiency Levels as A,B,C or D

A - Excellent

B - Good

C - Average

D - Should Improve

120


Tools for Extended Teaching - Learning Process

1.0 Evaluation : Term 2, Instrument 3

2.0 Competency levels covered : 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.9, 3.10

Copyright © 2007 National Institute of Education - Sri Lanka. All rights reserved.

3.0 Subject content covered : • Classification of chemical reaction

• Investigate interactions between matter and

electricity.

• Investigate reaction pattern of pure metals

• Examine the rate of the reaction of chemical reac

tions.

• Get the necessary action to prevent metal corrision.

• Preparation of gases and examine properties.

• Invetigate Heat changes relevent to chemical

reactions

4.0 Nature of Instrument : Chemistry practical workshop

5.0 Objectives : 1. To develope practical experiences relevant to

various chemical reactions.

2. To enhance maniuplations skills for setting experimental

appratus.

3. To direct the students on effective communication

through creations.

6.0 Instrutions for implementation :

For teachers

• In this tool each student is involved in an individual

process as well as group process.

• Divide a class into seven groups and give the relevent

practical set.

• Provide the necessary facilities for practical test and

inform the students in advance the date at which they

have to conduct a workshop.

• Evaluate the students after the workshop.

For students

• Present the practical test which is preplaned given by

teacher.

• Get the chance to present the relevent activity accu

rately

• Preplanned when the result of experiment is taken

several days.

• Plan the workshop when result of some experiment

is taken several days.

121

More magazines by this user
Similar magazines