1. Electron Dot Diagrams / Lewis Structures
Atom and Covalent Compound diagramming

2. 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”

3. 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.

4. 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

5. 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.

6. Electron Dot Diagrams
Some electrons are already paired up within a single atom and are not shared. These are called non-bonding / unshared pairs.

7. Electron Dot Diagrams Some elements are able to share more than one
pair of electrons
to form double
and triple bonds

8. Electron Dot Diagrams 1. Carbon 6. Hydrogen 2. Nitrogen 7. Chlorine
Draw electron dot diagrams of the following elements:
1. Carbon 6. Hydrogen
2. Nitrogen 7. Chlorine
3. Phosphorus 8. Argon
4. Boron 9. Iodine
5. Oxygen Helium

9. Homework 1. CCl4 6. H2O 2. N2O2 7. CH4 3. PBr3 8. SO2 4. BI3 9. NH3
Draw electron dot diagrams of the following compounds:
1. CCl H2O
2. N2O2 7. CH4
3. PBr3 8. SO2
4. BI NH3
5. C3H6O 10. SiO4