Understanding Ionic Formulas

What is the charge of a sodium ion in the formation of sodium chloride?

• +2

• -1

• +1

• -2

Why do we need to adjust the subscripts in magnesium fluoride?

• Because magnesium and fluoride have equal charges

• Because magnesium has a +1 charge

• Because fluoride has a +2 charge

• Because their charges are not equal

In the formation of iron oxide, what is the charge of iron?

• +6

• -2

• +3

• +2

How many oxide ions are needed to balance the charge of iron in iron oxide?

• One

• Four

• Two

• Three

Why are parentheses used in the formula for calcium hydroxide?

• To separate calcium and hydroxide

• To balance the charge of calcium

• To show that two hydroxide ions are needed

• To indicate the presence of two calcium ions