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
Helium-has 2 electrons
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
Oxygen
Neon
Chlorine
Practice: Draw an electron
configuration and indicate the
number of valence electrons.
1)
Boron
2)
Lithium
3)
Nitrogen
4)
Aluminum
5)
Calcium
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)
Arrangement showing
valence electrons

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
The periodic table is also
organized to show electron
distribution