1. CHEM11 3-10 Some groups of atoms act as individual compounds e.g.SO 4 2- Sulphate ion OH - Hydroxide ion PO 4 3- Phosphate ion When writing formulas and naming, pretend the polyatomic ion is just one atom and follow the rules as usual. e.g. KPO 4 +3- K PO 4 13 K 3 PO 4 Potassium phosphate Don’t change the endings of polyatomic ions

2. CHEM11 3-11 Aluminum sulphate Copper II sulphate AlSO 4 3+2- Al SO 4 32 Al 2 (SO 4 ) 3 Cu 2+ Cu SO 4 22 Put brackets around the SO 4 to indicate 3 sulphate ions, not 43 oxygen atoms SO 4 2- Don’t forget the roman numeral since copper has more than one combining capacity See the back of your periodic table for the names and formulas of important polyatomic ions.

3. CHEM11 3-12 Hydrates are ionic compounds with water molecules attached e.g. - each copper II sulphate is attached to 5 water molecules CuSO 4 5H 2 O Copper II sulphate pentahydrate e.g. FeSO 4 6H 2 O Iron II sulphate hexahydrate

4. CHEM11 3-13 HCl HF HNO 3 Hydrochloric acid Hydrofluoric acid Nitric acid HNO 2 H 2 SO 4 Nitrous acid Sulphuric acid

5. SC10 3-15 Page 55 “Review & Practice” Q: 5-7 Worksheet (Q. 1-21 front, 1-26 back) Homework: