Screen shots from Heinemann Science Links 2 VELS Edition TRAD

Answers to text questions
Chapter 1 Chemical reactions
1.1 TYPES OF ELEMENTS
QUESTIONS
1 Matter refers to everything in the universe that
has mass (can be weighed) and volume (takes up
space). All matter consists of atoms and is in the
form of a solid, liquid or gas.
2 Individual student response (song, rap, poem or
drawing) required. Responses will vary but may
include the following information:
• Atoms are the building blocks of matter.
• An element is a pure substance composed of only
one type of atom; it cannot be broken down into
simpler substances so the song, rap, poem or
drawing should reflect this concept.
Encourage feedback from peers after students
have performed their song or poem etc.
3 The symbols for elements are derived from:
• The first one or two letters of the element’s
name, e.g. carbon C and Calcium Ca
• Their old Latin or German names, e.g. copper
Cu (Latin: cuprum) and tungsten W (German:
Wulfram)
• The names of famous people or places,
e.g. rutherfordium Rf and plutonium Pu.
4 (a) Ca, Fe, N, C, Pb, O
(b) Aluminium, gold, bromine, chlorine, copper,
mercury, potassium, phosphorus, sulfur, zinc
(c) Francium, californium and americium are
possible answers.
(d) Einsteinium, mendelevium, lawrencium are
possible answers.
(e) Metals: sodium; Non-metals: oxygen, carbon;
Metalloids: germanium, silicon
5 Individual student response (pamphlet) required.
Refer to the collaborative learning section in the
Skills link chapter and the VELS and Science
Links section of the TRAD for help with the
presentation of information, including pamphlets.
Responses will vary but may include the
following information:
• Metals are often shiny, malleable, ductile,
usually solid at room temperature and good
conductors of electricity and heat, e.g. copper.
Some uses of metals include construction
materials, water pipes, coins, containers and
jewellery.
• Non-metals that are solids at room
temperature are brittle, non-malleable, poor
conductors of electricity and cannot be drawn
into wires (e.g. sulfur). Some non-metals are
gases at room temperature (e.g. oxygen) and
others are liquids (e.g. bromine). Some uses
of non-metals include air balloons, explosives,
fertilisers and plastics.
• Metalloids have properties between those of
metals and non-metals. They are shiny, brittle,
and semi-conductors (e.g. silicon). Some uses
of metalloids include communication,
transistors, solar cells and computer chips.
6 Some pure metals are too soft and possess
insufficient strength for many engineering
purposes. Alloys are combinations of two or more
metals, or a metal and a non-metal, that have
desirable properties, such as greater strength,
hardness, lightness or resistance to corrosion.
Stainless steel is iron mixed with nickel and
chromium. It is strong and resistant to rusting,
therefore, it has a wide variety of uses.
7 Melting point, boiling point, malleability,
hardness, ductility, conductivity, magnetic
properties. Students should be able to describe
what each property means.
8 Malleability refers to the property of a metal that
makes it capable of being hammered or rolled
into shape (e.g. sheet metal) whereas ductility
refers to the ability of a metal to be drawn into
wires (e.g. power lines).
9 Individual student response (mind map) required.
For help with mind maps refer to the Graphic
organisers information in the VELS and Science
Links section of the TRAD. Responses will vary
but may include the following information about
the physical and chemical properties of graphite
and diamond, as well as their sources and uses:
• Carbon exists in several forms: diamond and
graphite are two crystalline forms of carbon.
• Diamond is the hardest natural substance
known. In the diamond crystal, each carbon
atom is linked tetrahedrally to four others.
Transparent diamonds are valuable
gemstones. Heavily coloured forms are used
for rock drills, lathe tools and for cutting and
polishing clear diamonds.
• Graphite consists of parallel hexagonal sheets
of carbon atoms. It is used in pencils,
electrical components, paints and as a
lubricant.
• Most non-metals usually don’t conduct heat
or electricity, but carbon is an exception. In
graphite, the carbon atoms are bonded in
sheets. Each carbon atom is bonded to three
other carbon atoms, forming covalent bonds.
The fourth electron of each carbon atom is
mobile across the sheet of carbon atoms,
forming an ‘electron sea’, which accounts for
the electrical conductivity of graphite.
Heinemann Science Links 2 TRAD Answers to text questions 2

Laboratory safety and practical advice
The following information is provided to assist teachers in assessing and reducing the safety risk of each
experiment. Any assessment of safety risk will need to take into account the circumstances under which the
experiment is conducted, including the students’ abilities and the teacher’s experience.
While every care has been taken in compiling this advice, no guarantee can be given against errors or
incompleteness, or that regulations and standards will not change. Teachers are encouraged to become
familiar with the regulations relating to dangerous goods and hazardous substances and to refer to the MSDS
supplied by the manufacturer before using any chemical in an experiment.
Designated hazardous substances are listed in bold. Dangerous goods are listed in italics. In some cases there
are no special risk control measures—the activity is not considered hazardous as long as correct procedures
are followed. This is indicated by RPP in the table. Rules, precautions and procedures (RPP) should be
established to minimise risk. Teachers should establish these rules, precautions and procedures and revise
them as necessary. Some of these are:
• the correct procedure for lighting and using a Bunsen burner, and safety precautions such as tying
back long hair, wearing suitable clothing (low flammability, no trailing sleeves) and footwear;
• care in handling fragile glassware—for example, placing empty test-tubes in racks so they will not
roll off the bench, etc.;
• safe use of the mains power supply—for example, operating switches with dry hands, not turning
switches on until instructed by the teacher, and inserting and removing plugs only when the switch is
turned off;
• the taping shut of exposed agar plates, and never opening them;
• the correct way to deal with chemical spills;
• the use of spatulas, etc. to transfer chemicals;
• the correct way to mix chemicals in a test-tube—by gentle swirling rather than placing fingers or
thumb over the mouth of the tube and shaking; and
• the correct way to smell gases—by wafting with the hand rather than sniffing directly.
Heinemann Science Links VELS 2 TRAD Laboratory safety and practical advice 1

HAZARDS AND SAFETY PRECAUTIONS
Experiment/activity Hazard Safety advice Practical notes/hints
Activity 1.1
Investigating elements
Fragile glassware (if glass
sample bottles used)
Calcium, magnesium and
sulfur are dangerous
substances.
Iodine is a designated
hazardous substance.
RPP
Reinforce warning not to
open bottles.
Be aware of the location of
the MSDS and spill kits in
case of breakages.
Inspect for chips and
cracks.
Refer students to the Skills
link chapter for help with
using graphic organisers
and a range of presentation
formats.
Experiment 1.3
Hot water
RPP
Properties of elements
Hammer
Sulfur is a dangerous
substance. It is easily
ignited and an irritant to
the respiratory system.
Zinc is harmful by
swallowing, inhalation and
contact with skin, irritating
to eyes and skin, risk of
damage to eyes.
Copper is harmful by
inhalation and swallowing.
Safety glasses must be
worn when polishing and
hammering samples.
Disposable gloves should
be worn when handling
chemicals, and hands
washed at the conclusion of
the experiment.
Warn against hitting
fingers with hammer and
inhaling dust when
polishing samples.
Lead is a designated
hazardous substance. It is
harmful by inhalation and
swallowing, irritant to eyes.
Experiment 1.4
What’s in a compound
Fragile glassware
Hydrochloric acid is a
designated hazardous
substance, corrosive,
causes burns, harmful by
inhalation at concentrations
equal to or more than
0.2%, irritating to eyes,
respiratory system and skin
at concentrations equal to
or more than 0.02% and
less than 0.2%.
RPP
Reinforce instructions not
to touch chemicals. Advise
students of procedures if
chemicals are accidentally
spilled.
Use dilute hydrochloric
acid (0.1 M).
RPP
Safety glasses should be
worn. Make sure that only
the specified quantities of
reactants are used.
Emphasise care to avoid
spills. If reagents are
spilled on skin, rinse with
copious amounts of water.
Refer students to the Skills
link chapter for help with
using a range of
presentation formats.
Heinemann Science Links VELS 2 TRAD Laboratory safety and practical advice 2