1. Polyatomic Ions - Groups of Atoms with a Charge CHEMISTRY

2. Common Polyatomic Ions NameFormulaNameFormula AmmoniumNH 4 +1 AcetateC 2 H 3 O 2 -1 ChlorateClO 3 -1 HydroxideOH -1 NitrateNO 3 -1 NitriteNO 2 -1 CarbonateCO 3 -2 SulfateSO 4 -2 SulfiteSO 3 -2 PhosphatePO 4 -3 Formulas containing polyatomic ions are similar to formulas without them.

3. Characteristics of Polyatomic Ions The oxidation number of a polyatomic ion is its Charge. Whenever a subscript is added to a polyatomic ion to make the total oxidation number in the formula equal zero, the ion MUST be enclosed with parenthesis, ( ). the formula for a compound composed of Calcium and Hydroxide Ion is Ca(OH) 2 Parenthesis, ( ), are not used if no subscript is added. the formula for a compound composed of Calcium and Carbonate Ion is CaCO 3

4. Write formulas for these:  Calcium Acetate  Ammonium Phosphate  Potassium Sulfate  Aluminum Nitrate  Copper (II) Chlorate  Iron (III) Phosphate  Barium Hydroxide  Copper (I) Sulfite  Mercury (III) Hydroxide  Chromium (II) Acetate  Tin (IV) Hydrogen Carbonate

5. Answers Ca(C 2 H 3 O 2 ) 2 (NH 4 ) 3 PO 4 K 2 SO 4 Al(NO 3 ) 3 Cu(ClO 3 ) 2 FePO 4 Ba(OH) 2 Cu 2 SO 3 Hg(OH) 3 Cr(C 2 H 3 O 2 ) 2 Sn(HCO 3 ) 4