Writing Formulas for Ionic Compounds

• Write the symbol for the metal and its charge followed by the symbol of the nonmetal and its charge.
• Make the magnitude of the charge on each ion (without the sign) become the subscript for the other ion.
• If possible, reduce the subscripts to give a ratio with the smallest whole numbers.
• Check to make sure that the sum of the charges of the cations exactly cancels the sum of the charges of the anions.