Electron Dot Diagrams / Lewis
Structures
Atom and Covalent Compound
diagramming
Electron Dot Diagrams

Shows valence electrons around an atom

Valence electrons – electrons in the outermost
energy level of an atom

Valence electrons are only located in the outer
level “s” and “p” orbitals

Valence electrons are shown in the outer
energy level of a “shell diagram”
Electron Shell Diagrams

A shell diagram
shows all electrons,
but we are most
interested in the
electrons in the
outermost energy
level  called the
valence level or
valence shell.
Electron Dot Diagrams

To draw:
1. Write chemical
symbol
2. Place one dot around
chemical symbol for
each valence electron
(up to eight dots)
3. All inner level electrons
and nucleus are
symbolized by the
chemical symbol
Electron Dot Diagrams

Line up single dots
to form compounds
and to make either 2
or 8 electrons
around each
element. The
elements share their
single unpaired
electrons.
Electron Dot Diagrams

Some electrons are already paired up within a
single atom and are not shared. These are
called non-bonding / unshared pairs.
Electron Dot Diagrams

Some elements
are able to share
more than one
pair of electrons
to form double
and triple bonds
Electron Dot Diagrams

Draw electron dot diagrams of the
following elements:
1. Carbon
2. Nitrogen
3. Phosphorus
4. Boron
5. Oxygen
6. Hydrogen
7. Chlorine
8. Argon
9. Iodine
10. Helium
Homework

Draw electron dot diagrams of the
following compounds:
1. CCl4
2. N2O2
3. PBr3
4. BI3
5. C3H6O
6. H2O
7. CH4
8. SO2
9. NH3
10. SiO4