Understanding Formal Charge

What is the primary purpose of formal charge in chemistry?

• To determine the mass of an atom

• To act as a fictitious bookkeeping tool

• To measure the actual charge of an atom

• To serve as a real charge indicator

How is the formal charge of an atom calculated?

• By dividing the number of neutrons by electrons

• By adding the number of protons and electrons

• By multiplying the atomic number by the number of bonds

• By subtracting the number of formal electrons from valence electrons

What must the sum of formal charges in a molecule equal?

• The atomic number of the central atom

• The total number of bonds

• The overall charge of the molecule or ion

• The number of lone pairs

Which Lewis structure is considered the best?

• The one with the most lone pairs

• The one with the highest atomic number

• The one with the fewest nonzero formal charges

• The one with the most bonds

In the water molecule example, what is the formal charge of the oxygen atom?

• -1

• +2

• +1

• 0

How many valence electrons does oxygen have in the water molecule example?

• 2

• 6

• 4

• 8

In the nitrate ion example, what is the formal charge of the central nitrogen atom?

• +2

• +1

• 0

• -1

How many lone pairs are on each of the equivalent oxygen atoms in the nitrate ion?

• 3

• 2

• 1

• 4

What is the total charge of the nitrate ion?

• -1

• +1

• 0

• +2

Why do equivalent atoms in a molecule have the same formal charge?

• They are in different groups of the periodic table

• They have different electronegativities

• They have the same number of bonds and lone pairs

• They have different numbers of bonds