A Little Review:

• The Atomic Number is equal to the # of protons, which also equals the # of electrons

• The Atomic Mass is calculated using the formula protons + neutrons

•Both protons and neutrons are found in the nucleus

•protons p+ neutrons n0 electrons e-

• Electrons are found moving around in the cloudlike region outside of the nucleus

• 18 Groups (top to bottom) aka “Families”• 7 Periods (right to left, like reading)

• 3 types of Elements Metals, Metalloids, Nonmetals

ElectronsDetermining Shells and Valence Electrons

Electrons are negatively charged particles that are found moving outside of the nucleus

e- are 2000x smaller than p+ and n0

Electrons are found in shells

Electrons in the outer most shell are called:Valence Electrons

Periods determine the # of Shells

1st Period = 1 Shell2nd Period = 2 Shells3rd Period = 3 Shells4th Period = 4 Shells

•The elements in each period have the same number of shells

Groups determine Valence e-

•Each element in a group has the same number of electrons in their outer orbital, also known as “shells”.

Group 1 = 1 electronGroup 2 = 2 electrons

Group 8 = 8 electrons

Exception He, it has 2 electrons3, 4, 5, 6, 7

The Magic Numbers to Remember

2 - 8 - 8 1st shell can hold a max of 2e-

2nd shell 8e- 3rd shell 8e- … 2-8-8

Determine the number of shells and the number of valence e- for:

Carbon, C

2nd Period = 2 shells

4th Group = 4 valence e-

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Determine the number of shells and the number of valence electrons for:

Sodium, Na

3rd Period = 3 shells

1st Group = 1 valence electron

Na is Atomic #11, p=e, so there are also 11 electrons

Name the Element:

# of Shells = ________

# of Val. e- = ________

Name ______________

Symbol _____

Name the Element:

# of Shells = ________

# of Val. e- = ________

Name ______________

Symbol _____

Starter #

Starter #