10 e. iron (II) sulfate

the Roman numeral indicates the charge of the iron;

all compounds must be neutral; need to make total positive charge equal total negative charge

for polyatomic ions, if you need to indicate more than one in a formula, put parentheses around the polyatomic ion and put the subscript to indicate how many outside the parentheses.

Fe²⁺ and SO₄^2-

need one iron and one sulfate

FeSO₄