summary of how to balance redox

1. Determine the oxidation numbers of all atoms and tag the atoms that change oxidation numbers
2. Split those tagged atoms out into the two half (cell) reactions
Do steps 3 through 6 for each half (cell) reaction
3. Balance the atom which changes oxidation number.
4. Add	on the left for the reduction		electrons equal to the change in oxidation number (each) times the number of atoms that change oxidation number (total.)
	on the right for oxidation
5. Balance the spectator ions such as Cl^-, OH^-, H⁺, etc.
6. Balance the oxygen by:		in acid: adding 1 H₂O for each O and 2 H⁺ on the other side.
		In base: adding 2 OH^- for each O and 1 H₂O on the other side.
The half cells should be balanced at this point. To get the overall reaction:
7. Add the two half reactions together such that the electrons cancel. (Find a common factor.)

Here is a repeat of the lazy person's guide to oxidation numbers of atoms in compounds and ions.:

This list is a hierarchy, if there is a conflict between rules, the first listed rules.
The oxidation numbers for a compound add up to zero and for an ion to the charge.
fluorine has an oxidation number of -1
Group 1 metals have an oxidation number of +1
Group 2 metals have an oxidation number of +2
Sc, Y and Al have an oxidation number of +3
H is +1 when bonded with a nonmetal and -1 when bonded with a metal
Oxygen has an oxidation number of -2 (learn the polyions)
Group 17 nonmetals have an oxidation number of -1
Group 16 nonmetals have an oxidation number of -2
Group 15 nonmetals have an oxidation number of -3
Carbon has an oxidation number of -4

The polyion chart:

Others:

hydroxide: OH^- hydronium: H₃O⁺ ammonium: NH₄⁺

Some special polyions for which O does not have an oxidation number of -2

peroxide O₂^2- superoxide O₂^-