1. Electron Configurations and Lewis Dot Diagrams

2. Electron Configurations
Electrons are key players in chemical bonding. To predict how atoms will bond, we use a configuration. These show how the electrons are arranged around the nucleus
Electrons are arranged in shells, levels or orbitals
How do we know how many electrons an atom has?
Different levels can hold different numbers of electrons:
level 1-can hold 2 electrons
level 2-can hold 8 electrons
level 3-can hold 18 electrons
Note: There are more levels or obitals-formula to determine
the amount of electrons in each level is 2n2
Electron Configurations

3. Helium-has 2 electrons

4. Oxygen

5. Neon

6. Chlorine

7. Valence Electrons
The electrons on the outer shell/level are called valence electrons.
Bonding between atoms occurs between valence electrons in atoms.
An atom with a full outer shell will be stable-will not bond with other atoms.
Example: Argon-has 8 valence electrons
Example: Neon-has 8 valence electrons

8. Lewis Structures Find your element on the periodic table.
Determine the number of valence electrons.
This is how many electrons you will draw.

9. Lewis Structures Find out which group (column) your element is in.
This will tell you the number of valence electrons your element has.
You will only draw the valence electrons.

10. Groups - Review Group 8 = 8 electrons Group 1 = 1 electron
Except for He, it has 2 electrons
Group 2 = 2 electrons
Each column is called a “group”
3, 4, 5, 6, 7
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”

11. C Lewis Structures Write the element symbol.
Carbon is in the 4th group, so it has 4 valence electrons.
Starting at the right, draw 4 electrons, or dots, counter- clockwise around the element symbol. C

12. Practice: Draw an electron configuration and Lewis Dot Diagram
Boron
Lithium
Nitrogen
Aluminum
Calcium

13. Groups on the Periodic Table
Group 1-has 1 valence electron
Group 2-has 2 valence electrons
Groups 3-12-have 2 or more valence electrons
Group 13-has 3 valence electrons
Group 14-has 4 valence electrons
Group 15-has 5 valence electrons
Group 16-has 6 valence electrons
Group 17-has 7 valence electrons
Group 18-has 8 valence electrons (except Helium)

15. Arrangement showing valence electrons

16. When you take high school chemistry, you
will learn more about the orbitals and how electrons
are distributed around the nucleus. You will also
learn how to write the configurations:
1s2, 2s2, 2p6, 3s2, 3p6, 3d 10

17. The periodic table is also organized to show electron distribution