1. Polyatomic Compounds Polyatomic ions are groups of atoms that stay together and have an overall ionic charge. Ex: Nitrate (NO 3 - )

2. When compounds containing nitrate are dissolved in water: 1)The positive metal ion and the nitrate ion separate 2)The nitrate ion itself stays together

3. Writing Formulas: Ex: Na & SO 4 1)Write the symbols of the metal and of the polyatomic group. 2)Write the ionic charge 3)Choose the number of ions to balance the charge 4)Write the formula using subscripts

4. Crisscross rule: Ex: NaSO 4 *How far can it be reduced?

5. Naming Polyatomic Compounds: The name is a combination of the name of the metal and the name of the polyatomic ion. Always name the positive part first, and the negative part second. Ex: K + and CO 3 2- NH 4 + and NO 3 -

6. More examples: lead (IV) carbonate

7. Homework: Polyatomic Ion Worksheet