1. Ionic Compounds with Polyatomic Ions

2. What is a polyatomic ion? 0 Polyatomic Ion: 0 An ion consisting of 2 or more atoms chemically bonded together and carrying a net electric charge. 0 Example: 0 Nitrate = NO 3 -1 0 Sulfate = SO 4 -2 0 Cyanide = CN -1 0 Ammonium = NH 4 +1 0 Oxyanion: 0 A polyatomic ion containing at least one oxygen atom and one or more atoms of at least one other element

4. Naming Compounds with Polyatomic Ions: 0 When naming polyatomic ions, do not change ending of name. It should match letter for letter from chart. 0 Do not forget other naming rules. 0 Example: 0 Ca(C 2 H 3 O 2 ) 2 0 Calcium acetate 0 NH 4 NO 3 0 Ammonium nitrate

5. Learning Check 0 Name the following compounds: 1. Ca(CN) 2 2. (NH 4 ) 2 O 3. AlPO 4 4. Li 2 CO 3 5. (NH 4 ) 2 Cr 2 O 7 Answers: 1. Calcium cyanide 2. Ammonium oxide 3. Aluminum phosphate 4. Lithium carbonate 5. Ammonium dichromate

6. Writing Formulas 0 The goal is still to balance charges. 0 Use same procedure as binary compounds however… 0 A parentheses must be placed around the polyatomic ion if you need more than one to balance charges. (if adding another subscript) 0 Do not change subscripts on polyatomic ion! 0 Example: 0 Magnesium nitrate

7. More Examples 1. Calcium chlorate 2. Lead (II) acetate 3. Ammonium chromate 4. Magnesium sulfate