1. Writing Ionic Formulas from Names

2. Steps for Writing Ionic Formulas from Names Write the formula for the cation (metal) including the charge Write the formula for the anion (non-metal or polyatomic ion) including the charge Use the criss-cross method to balance the charges.

3. Examples 1. Write the formula for Potassium Oxide 2. Write the formula for Tin (II) Chloride *Note: Roman numeral is the charge on the cation Tin (II) = Sn 2+ K + O 2- K2OK2O Sn 2+ Cl - SnCl 2

4. 3. Write the formula for Aluminum Sulfate (note: Sulfate is a polyatomic ion!) 4. Write the formula for iron (III) sulfide 5. Write the formula for calcium hydroxide Al 3+ SO 4 2- Al 2 (SO 4 ) 3 Fe 3+ S 2- Fe 2 S 3 Ca 2+ OH - Ca(OH) 2