Electron Dot and Structual
Diagrams for Covalent
Compounds
Lewis Structures
-
• Structural Diagrams show the number of
bonds in a compound.
H- O
H
• Electron Dot Diagrams show the electrons
involved in the bonds of compounds.
:
1 pair of electrons = 1
bond
:
Bonding
e-
H: O:
H
Non-bonding e- or
lone pairs
Electron Dot Diagrams
Determine the number of valence e- for an element.
1e2e-
valence
electrons
7e- 8e3e- 4e- 5e- 6e-
Electron Dot Diagrams
Determine the number of valence e- for an element.
# valence e-
H
Cl
1
7
F S
7
6
O
P N C
Si
6
5
4
5
4
: .
: .
.
.
.
.
: .
: .
: :
: :
.
3
3
4
4
H . Cl : . F : . S : . O: . P . . N. . C . . Si .
# of bonds
1
1
1
2
2
When drawing structural diagrams, each element must have the
correct number of bonds.
Electron Dot Diagrams
Each bond in the structural formula represents
two electrons.
All valence electrons must be used
Each element must have a full valence orbital
(8e-) , except H (2e-)
Try C2H6
First, determine the central atom (the one with
the most bonding electrons):
Carbon 4 e-
Hydrogen 1 eSo the central atoms will be?
C
Electron Dot Diagrams
C2H6
.
. .
.
C
Electron Dot Diagrams
C2H6
. .
.
.
. .
.
C C.
Electron Dot Diagrams
C2H6
..
..
H H
H C C.H
All atoms have a
H H full shell
.
..
..
..
..
Electron Dot Diagrams
C2H6
..
..
H H
H C C.H
All atoms have a
H H full shell
.
..
..
..
..
Electron Dot Diagrams
A structural diagram is one that shows each bond as
a line. Each line represents 2 bonding electrons.
Lone pairs are not shown in a structural diagram
C2H6
H H
H C C H
H H
Electron Dot Diagrams
HCN
Electron Dot Diagrams
HCN
Electron Dot Diagrams
HCN
H
C
N
Electron Dot Diagrams
HCN
.
..
..
H C
Electron Dot Diagrams
HCN
N
..
....
..
H C
Electron Dot Diagrams
HCN
H
C
N
..
..
....
..
H C
N
Atoms have full shells
All valence electrons
were used
Electron Dot Diagrams
Try drawing the electron dot diagram for:
CO2
Electron Dot Diagrams
Try drawing the electron dot diagram for:
CO2
O
C
O
Electron Dot Diagrams
Try drawing the electron dot diagram for:
CO2
..
..
....
..
..
..
.
.
O
C O
Atoms have full shells
All valence electrons
were used
Electron Dot Diagrams
Try drawing the electron dot diagram for:
CO2
C O
C O
..
..
....
..
..
..
.
.
O
O
Atoms have full shells
All valence electrons
were used
Electron Dot Diagrams
Try drawing the electron dot diagram for:
N2
Electron Dot Diagrams
Try drawing the electron dot diagram for:
N2
N
N
Electron Dot Diagrams
Try drawing the electron dot diagram for:
N2
N
..
..
....
..
N
Atoms have full shells
All valence electrons
were used
Electron Dot Diagrams
Try drawing the electron dot diagram for:
N2
N
N
..
..
....
..
N
N
Atoms have full shells
All valence electrons
were used
Electron Dot Diagrams
Try drawing the electron dot diagram for:
P2O3 (sym)
Electron Dot Diagrams
Try drawing the electron dot diagram for:
P2O3
O
P
O
P
O
Hint: This molecule is symmetrical…which means
an O will be in the center.
Electron Dot Diagrams
Try drawing the electron dot diagram for:
P2O3
..
..
.. ..
..
.
.
.. ..
..
..
....
..
..
O P O P O
Electron Dot Diagrams
Try drawing the electron dot diagram for:
P2O3
O
P
O
P
..
..
.. ..
..
.
.
.. ..
..
..
....
..
..
O P O P O
O
Electron Dot Diagrams
Try drawing the electron dot diagram for:
C4H8 (cyclic)
Electron Dot Diagrams
H
..
..
..
. . ..
..
H
H
..
H C
..
H
..
Try drawing the electron dot diagram for:
C4H8 (cyclic)
..
..
..
H C
C H
C H
Electron Dot Diagrams
Try drawing structural diagrams for the
following: C4H8 (cyclic)
H
H
H C
C H
H C
C H
H
H