Oxidation happens at the positive anode because this is where negative ions lose electrons.
Positively charged ions gain electrons at the cathode. These are half equations for some reactions at the cathode:
Na+ + e- → Na
Pb2+ + 2e- → Pb
Balance the half equation for the formation of aluminium during electrolysis: Al3+ + e- → Al.
The balanced half equation is: Al3+ + 3e- → Al (because three negatively charged electrons are needed to balance the three positive charges on the aluminium ion).
Write a balanced half equation for the formation of calcium from a calcium ion, Ca2+.
Ca2+ + 2e- → Ca
Negatively charged ions lose electrons at the anode. These are half equations for some reactions at the anode:
2Cl- → Cl2 + 2e-
2O2- → O2 + 4e-
Write a balanced half equation for the formation of bromine, Br2, from bromide ions, Br-.
2Br- → Brl2 + 2e-