Lewis Structures = Dot Diagrams

• We can show how the atoms share or transfer electrons by drawing electron dot diagrams.

• You will only use the valence e- for dot diagrams.

Dot Diagrams

• Start the dot diagram by writing the atomic symbol for the atom.

Ex: Mg

The symbol has 4 sides…

Dot Diagrams

Mg

Each side can hold up to 2e- for a maximum of 8e-.

You cannot pair the electrons until there is one on each side.

Dot Diagrams

Mg

Mg only has 2 valence e-.

So its dot diagram looks like this: Mg

Dot Diagrams

• Lets Practice!!! Draw the Dot Diagrams for:

1.) Cl 4.) C2.) Al 5.) Ne3.) Na

Dot Diagrams

• How did you do???

1. Cl 4.) C

2.) Al 5.) Ne

3.) Na

Dot Diagrams

Now we can put individual diagrams together to show whether atoms transfer (ionic bonds) or share (covalent bonds) their valence e-!!!

Bonding Dot Diagram Steps1.) Identify the type of bond you have. (Covalent or Ionic)

2.) Separate the individual elements and put them in a line or box formation. Put the atomic symbol w/ least amount of valence e- in CENTER!!! (Remember H’s have to be on ENDS!!!)

3.) Draw the “dots” for each atomic symbol.

4.) Locate all of the “lonely e-”. Show either the transferring or sharing of e- with arrows or bars. (If sharing…connect the “lonely” dots between DIFFERENT symbols!!!)

5.) For COVALENT: Count the e- around each atomic symbol to make sure there are 8!!! (ONLY 2 for H!!!)

Dot Diagrams for Ionic Bonds

We know that in an Ionic Bond (metal +nonmetal) atoms are transferring their valence e- …

We can show this w/ dot diagrams.

For Ex: (Li + Cl = LiCl)

Li Cl

Dot Diagrams for Covalent Bonds

We know that in a Covalent Bond (nonmetal + nonmetals) atoms are sharing their valence e- …

We use a BAR written between the Atomic Symbols to represent the sharing of e-.

One bar = 2 e-

For Ex: H2O

Dot Diagrams for Covalent Bonds

One bar = 2 e-.

For Ex: H2O

H O H

***H’s ALWAYS have to go on the ENDS.

Dot Diagram Practice

1.) CaCl2

2.) SiO2

3.) NH3

4.) Na3N