Chemical formulae of ionic compounds: iron (III) chloride FeCl3 nickel (II) oxide NiO chromium (VI) oxide CrO3 silver (II) chloride AgCl2 vanadium (II) bromide VBr2 zinc (I) sulphate Zn2SO4 iron (III) hydroxide Fe(OH)3 manganese (II) oxide MnO manganese (III) oxide Mn2O3 copper (II) sulphate CuSO4 mercury (II) chloride HgCl2

2. Write a formula for the following pairs of ions and then write a name for them. Remember, only compounds of transition metals need the Roman numerals. The first one is done for you. Cu2+ and Cl- CuCl2 copper (II) chloride Ti2+ and O2- TiO titanium (II) oxide Ca2+ and S2- CaS calcium sulphate Na ion and N3- Na3N sodium nitride Mg ion and OH- Mg(OH)2 magnesium hydroxide Zn2+ and (NO3-) Zn(NO3)2 zinc (II) nitrate K+ and F- KF potassium fluoride

3. a) magnesium (Mg2+) and chloride (Cl-) ions b) Magnesium is in group 2 and always has a valency of 2. c) It is too reactive and bonded too strongly to the chlorine. d) On following slide

Electrolyte (magnesium chloride solution) negative electrode positive electrode Mg2+ + 2e- → Mg 2Cl- → Cl2 + 2e- Cl- Electrolyte (magnesium chloride solution) Mg2+ Cl- Mg2+