Electron Dot and Structual Diagrams for Covalent

Compounds

Lewis Structures

• Structural Diagrams show the number of bonds in a compound.

• Electron Dot Diagrams show the electrons involved in the bonds of compounds.

H:

H

:O:

:

H-

H-O

Non-bonding e- or lone pairs

Bonding e-

1 pair of electrons = 1 bond

Electron Dot DiagramsDetermine the number of valence e- for an element.

1e-

2e- 3e- 4e- 5e- 6e-

7e- 8e- valence electrons

Electron Dot DiagramsDetermine the number of valence e- for an element.

H Cl F S O P N C Si# valence e- 1 7 7 6 6 5 5 4 4

Cl

:

. :: H

.

F

:

. :: : S:

. . : O

:. . . P

:

. . . N

:

. . . C

.

. . .Si

.

. .

# of bonds 1 1 1 2 2 3 3 4 4

When drawing structural diagrams, each element must have the correct number of bonds.

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

Electron Dot Diagrams

First, determine the central atom (the one with the most bonding electrons):

Carbon 4 e-

Hydrogen 1 e-

So the central atoms will be? C

C2H6

C. ..

.

Electron Dot Diagrams

C .. C.

.. .

..

C2H6

Electron Dot Diagrams

C2H6

C .. C. .

. H H. .

.

H H

H H. ...

..All atoms have a full shell

Electron Dot Diagrams

C2H6

C .. C. .

. H H. .

.

H H

H H. ...

..All atoms have a 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

Electron Dot Diagrams

C

H

H

H

H

C

H

H

Electron Dot Diagrams

HCN

Electron Dot Diagrams

HCN

HCN

C

Electron Dot Diagrams

N

H

HCN

C. H

. . . .

Electron Dot Diagrams

HCN

C. H N

. . . ... .

Electron Dot Diagrams

HCN

C. H N

. .. . . ... .Atoms have full shells

All valence electrons were used

Electron Dot Diagrams

CH N

Try drawing the electron dot diagram for:

CO2

Electron Dot Diagrams

Try drawing the electron dot diagram for:

CO2

Electron Dot Diagrams

O C O

Try drawing the electron dot diagram for:

CO2

C

.

O

. . ... . O.. . ... .. .

Electron Dot Diagrams

Atoms have full shells

All valence electrons were used

Try drawing the electron dot diagram for:

CO2

C

.

O

. . ... . O.. . ... .. .

Electron Dot Diagrams

C OO

Atoms have full shells

All valence electrons were used

Try drawing the electron dot diagram for:

N2

Electron Dot Diagrams

Try drawing the electron dot diagram for:

N2

Electron Dot Diagrams

N N

N

.

N.. . . ... ..

Electron Dot DiagramsTry drawing the electron dot diagram for:

N2

Atoms have full shells

All valence electrons were used

N

.

N.. . . ... ..

Electron Dot Diagrams

N N

Try drawing the electron dot diagram for:

N2

Atoms have full shells

All valence electrons were used

Try drawing the electron dot diagram for:

P2O3 (sym)

Electron Dot Diagrams

Try drawing the electron dot diagram for:

P2O3

Electron Dot Diagrams

O P O P O

Hint: This molecule is symmetrical…which means an O will be in the center.

Try drawing the electron dot diagram for:

P2O3

O

.

P P

. . .. ....O O... . . .. .

. .. .

. ...

. . .

Electron Dot Diagrams

Try drawing the electron dot diagram for:

P2O3

O

.

P P

. . .. ....O O... . . .. .

. .. .

. ...

. . .

Electron Dot Diagrams

PO O OP

Try drawing the electron dot diagram for:

C4H8 (cyclic)

Electron Dot Diagrams

Try drawing the electron dot diagram for:

C4H8 (cyclic)

.

C C

CCH

H H

H

H

HH

H.

..

. ..

.

.. ..

.. .

...

.. .

...

Electron Dot Diagrams

Try drawing structural diagrams for the

following: C4H8 (cyclic)

C C

CCH

H H

H

H

HH

H

Electron Dot Diagrams