ELECTRON (LEWIS) DOT DIAGRAMS
VALENCE ELECTRONS
valence electrons – electrons in the highest unfilled energy
level
-These are the electrons that make chemical bonds.
Lithium (Li)
1s22s1
What is the highest energy level
that has electrons?
2
How many valence electrons
1
does lithium have?
3 WAYS TO DETERMINE VALENCE ELECTRONS
1) Given a Bohr model, count the
electrons in the outer energy level.
2) Given an Electron
Configuration, count the electrons
in the highest energy level.
3) Use the Periodic Table.
DRAWING LEWIS DOT DIAGRAMS
1) Given a Bohr model, count the
electrons in the outer energy level.

How many electrons are
in sodium’s outer energy
level?
1

What does the electron
dot diagram look like?
Na
DRAWING LEWIS DOT DIAGRAMS
2) Given an Electron Configuration, count the
electrons in the highest energy level.

Carbon’s electron
configuration is:

2 + 2=4
1s22s22p2
 What
is the highest
ENERGY LEVEL in
carbon?
2
How many electrons are
in carbon’s highest
energy level?

What does the electron
dot diagram look like?


C

DRAWING LEWIS DOT DIAGRAMS
3) Use the Periodic Table.
STEP
EXAMPLE
A) What column on the
PToE is the element
in?

What column is carbon
in?
Column 14
DRAWING LEWIS DOT DIAGRAMS
3) Use the PToE.
STEP
EXAMPLE
B) Use the following table
to determine how
many valence
electrons that column
has.

Column 1 2
Valence 1 2
Electrons
13
3
Carbon – Column14
How many valence
electrons do elements in
column 14 have? 4
14
4
15
5
16
6
17
7
18
8
DRAWING LEWIS DOT DIAGRAMS
3) Use the PToE.
STEP
C) Draw the Electron
(Lewis) Dot Diagram.
Start on one side and work
your way around.
EXAMPLE
DRAWING LEWIS DOT DIAGRAMS
3) Use the PToE.
1-4 Valence Electrons:
No more than 1 dot per side.

Carbon – 4 Valence
electrons
C
5-8 Valence Electrons
Some sides will have 2 dots.

Sulfur – 6 Valence
electrons
S
DRAWING ELECTRON DOT DIAGRAMS
Draw the Dot Diagram for magnesium (Mg).
Electron Configuration: 1s22s22p63s2
Highest Energy Level: 3
Electrons in Highest Energy Level: 2
Column Number: 2
Valence Electrons: 2
Mg
DRAWING ELECTRON DOT DIAGRAMS
Draw the Dot Diagram for arsenic (As).
Electron Configuration: 1s22s22p63s23p64s23d104p3
Highest Energy Level: 4
Electrons in Highest Energy Level: 2 + 3 = 5
Column Number: 15
Valence Electrons: 5
As
DRAWING ELECTRON DOT DIAGRAMS
Draw the Dot Diagram for helium (He).
Electron Configuration: 1s2
Highest Energy Level: 1
Electrons in Highest Energy Level: 2
Column Number: 18
He:
Note: Helium is weird! It doesn’t
follow the pattern.