V. Valence Electrons

A. Valence Electrons

• Valence electrons – found in the OUTERMOST (highest) energy level (sometimes called a shell)

• Located in highest s and p sublevels• These electrons are used for bonding• Elements range from having 1 – 8 valence electrons– Example: • Nitrogen: 1s2 2s2 2p3

• Nitrogen has 2 + 3 = 5 valence electrons

B. Valence Electrons From Noble Gas Configurations

• PRACTICE: # Valence e-Na [Ne]3s1

Mg [Ne]3s2

Al [Ne]3s23p1

Ca [Ar]4s2

Br [Ar]4s23d104p5

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C. Valence Electrons From Periodic Table

D. Lewis Dot Diagrams

• Lewis Dot Diagrams – way to visually represent valence electrons in an atom.

• Dots around element symbol = valence electrons• Max of 8 electrons around symbol : OCTET RULE

2nd Period Lewis Dot Diagrams

Li

ON

Be

F Ne

B C

Practice• Write the Lewis Dot Diagram for the following

elements

– Krypton

– Calcium

– 1s22s22p63s23p4

– [Ar] 4s23d104p5

– Antimony (Sb)

Due by the END of Class!

Write the Noble Gas Configuration, orbital diagram, and Lewis Dot Structures (valence electrons) for these elements:Li O Si P K

Se Sr I Ba Sn