Valence Electrons

Valence Electrons

Atoms want it all...

or nothing at all

What are valence electrons?

• the electrons in the outermost shell

• Shell is another way to say energy levels

• Atoms want to have a stable outer shell of electrons

What makes an outer shell stable?

• Being completely full of electrons

• or just having full s and p subshells/sublevels (they mean the same thing)

• Noble Gases have 8 valence electrons - full s and p subshells

• Atoms want to have a "Noble Gas" configuration

So how do atoms become stable?

• They will either gain electrons and become anions (negatively charged)

• or they will give up electrons and become cations (positively charged)

• Groups 1-3 (or 1A-3A) give up electrons - gets them to having 8 electrons in their outer shell

• Groups 15-17 (or 5A-7A) gain electrons - their outer shell becomes empty, so the shell below it becomes the new outer shell, it is already full

How many valence electrons do neutral atoms have?

• Old group (groups are columns) number (1A-8A) = number of valence electrons

• Lithium- 1 valence electron

• Beryllium - 2 valence electrons

• skip across to Boron - 3 valence electrons

• Carbon - 4; Nitrogen - 5; Oxygen - 6; Fluorine - 7; Neon - 8

Determine number of valence electrons with electron configurations

• Find the highest shell number (the first number in a term)

• (1s2 - shell number is 1; 3p4 - shell number is 3)

• Add the number of electrons in that shell

• ex. 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p3

• highest shell number is 4, so add 4s2 (2 electrons) and 4p3 (3 electrons) = 5 valence electrons

Multiple Choice

The electron configuration of an atom is 1s²2s²2p⁶.  The number of electrons in the atom is 

• 3
• 6
• 8
• 10

Multiple Choice

What electron configuration matches an oxygen atom?

• 1s²2s²2p⁶3s2, 3p⁶4s²3d¹⁰4p⁵

• 1s²2s²2p⁴

• 1s²2s²2p⁶

• 1s²2s²2p⁶3s²3p⁶4s²3d¹

Multiple Choice

How many Valance electrons does Iodine Have?

• 6
• 16
• 7
• 17

Multiple Choice

How many valence electrons are found in atoms of group 1?

• 7
• 6
• 4
• 1

Multiple Choice

How many valence electrons are in an atom of Ar?

• 2
• 8
• 4
• 1

Multiple Choice

USE THE PERIODIC TABLE

How many valence electrons does Phosphorus have?

• 31

• 5

• 15

• 4

Multiple Choice

How many valence electrons does carbon have?

• 4

• 5

• 6

• 7

Multiple Choice

• 2
• 3
• 5

Multiple Choice

• 2
• 8
• 3
• 13

Multiple Choice

What are valence electrons?

• The total number of electrons in an atom

• The number of electrons in the outermost shell

• The number of electrons in the second shell

• The number of protons in the outermost shell

Multiple Choice

How many valence electrons are in the following configuration?

1s2 2s2 2p6 3s2

• 6

• 8

• 2

• 12

Multiple Choice

How many valence electrons are in the following electron configuration?

[Kr] 5s2 4d10 5p2

• 4

• 10

• 2

• 12