1. Adapted from Mrs. LaRose, www.middleschoolscience.com 2008
Lewis Dot Diagrams
December 2nd, 2016
Adapted from Mrs. LaRose,

2. Lewis Dot Diagrams
A diagram to tell you the number of valence electrons an element has

3. Review: What are groups & valence electrons?
• Each column is called a “group”
• Each element in a group has the same number of electrons in their outer orbital, also known as “shells”.
• The electrons in the outer shell are called “valence electrons”
Group 1 = 1 electron
Group 8 = 8 electrons
Group 2 = 2 electrons
Except for He, it has 2 electrons

4. Write the element symbol.
Lewis Dot Diagrams
Write the element symbol.
• Find out which group (column) your element is in.
• This tells you the number of valence electrons it has.
• You will only draw the valence electrons.
Carbon is in the 4th group, so it has ____ valence electrons.
Draw 4 electrons, or dots, counter-clockwise around the element symbol.
DON'T PAIR THEM UP UNTIL EACH SIDE HAS ONE

5. In your notebook, try these elements on your own:
H P Ca
Ar Cl Al

6. Practice – ANSWER KEY

7. Lewis Dot Structures
A diagram that shows you the bonding between atoms of a molecule and the lone pairs of electrons that may exist in the molecule.

8. Count all valence electrons. Determine the central atom.
Lewis Dot Structures
Count all valence electrons.
Determine the central atom.
• Carbon • Electronegativity
Bond terminal atoms – update electron count (each bond is 2 electrons)
Add remaining electrons as lone pairs (start with outside and work in)
Check for octets – make multiple bonds if needed

9. Example 1: NH3
Example 2: CO2