Chemistry 201 Miss Stephens Monday, 21 February 2011

student.kc.school.nz

Chemistry 201 Miss Stephens Monday, 21 February 2011

Chemistry 201

Miss Stephens

Monday, 21 February 2011


1) Find your element on the periodic table.

2) Determine the number of valence electrons.

3) This is how many electrons you will draw.


• Find out which group

(column) your

element is in.

• This will tell you the

number of valence

electrons your

element has.

• You will only draw

the valence

electrons.


The electrons in the outer shell are called “valence electrons”

Group 1 = 1 valence electron

Group 8 = 8 valence electrons

Group 2 = 2 valence electrons

Except for

He, it has 2

electrons

Each column is

called a

“group”

Each element in a group has the same number of electrons

in their outer orbital, also known as “shells”.


1) Write the element

symbol.

2) Carbon is in the 4 th

group, so it has 4

valence electrons.

3) Starting at the right,

draw 4 electrons, or

dots, counterclockwise

around

the element symbol.


1) Check your work.

2) Using your periodic

table, check that

Carbon is in the 4 th

group.

3) You should have 4

total electrons, or

dots, drawn in for

Carbon.


Try these elements on

your own:

a) H

b) P

c) Ca

d) Ar

e) Cl

f) Al


Try these elements on

your own:

a) H

b) P

c) Ca

d) Ar

e) Cl

f) Al


Try these elements on

your own:

a) H

b) P

c) Ca

d) Ar

e) Cl

f) Al


Try these elements on

your own:

a) H

b) P

c) Ca

d) Ar

e) Cl

f) Al


Try these elements on

your own:

a) H

b) P

c) Ca

d) Ar

e) Cl

f) Al


Try these elements on

your own:

a) H

b) P

c) Ca

d) Ar

e) Cl

f) Al


Try these elements on

your own:

a) H

b) P

c) Ca

d) Ar

e) Cl

f) Al


We can use Lewis structures to show how

molecules and compounds bond.

Steps are:

1. Count up the total number of valence

electrons for all atoms.

2. Work out the type of bonding

3. Organize the atoms so there is a central atom.


The central atom usually has two or more valance

electrons. Hydrogen is never the central atom.

4. Arrange the electron pairs until all pairs have

been used:




One pair between the central atom and outer atom.

Three additional pairs on each outer atom (except H).

Remaining electron pairs (if any) on the central atom.


5. Connect all the atoms together in one

structure using bonding pairs symbolized

by a dash for each bonding pair and

double dots for each electron pair

6. Make sure each atom has a full outer

shell.

7. If not add a double bond until all atoms

have a full outer shell


Try to draw the electron dot diagram for

each of these:

1. CH 4

2. H 2 O

3. HCl


Try to draw the electron dot diagram for

each of these:

1. CH 4

2. H 2 O

3. HCl


Try to draw the electron dot diagram for

each of these:

1. CH 4

2. H 2 O

3. HCl

More magazines by this user
Similar magazines