Calculating Lone Pairs in Lewis Dot Structures

What is the formula to calculate the number of lone pairs on the central atom?

• Total valence electrons minus 4n divided by 4

• Total valence electrons minus 4n divided by 2

• Total valence electrons minus 8n divided by 4

• Total valence electrons minus 8n divided by 2

In the formula for calculating lone pairs, what does 'n' represent?

• Number of atoms in the molecule

• Number of valence electrons

• Number of lone pairs

• Number of atoms attached to the central atom

How many valence electrons are there in sulfur dioxide (SO2)?

• 22

• 20

• 18

• 16

How many lone pairs are on the sulfur atom in SO2?

• 0

• 3

• 1

• 2

How many valence electrons are there in nitrogen trifluoride (NF3)?

• 27

• 26

• 25

• 24

How many lone pairs are on the nitrogen atom in NF3?

• 0

• 1

• 2

• 3

How many valence electrons are there in xenon tetrafluoride (XeF4)?

• 32

• 34

• 36

• 38

How many lone pairs are on the xenon atom in XeF4?

• 2

• 4

• 1

• 3

How many valence electrons are there in the tri-bromide ion (Br3-)?

• 23

• 22

• 21

• 20

How many lone pairs are on the central bromine atom in Br3-?

• 5

• 4

• 3

• 2