Find the oxidation state of any atom in its elemental form: 0
Assign the oxidation state of a monatomic ion equal to its charge
Use these fixed values:
Group 1 metals: +1
Group 2 metals: +2
Fluorine: -1
Oxygen: usually -2
Hydrogen: usually +1
Chlorine, bromine, iodine: usually -1
Apply special cases:
Peroxides: oxygen is -1
Superoxides: oxygen is -1/2
Metal hydrides: hydrogen is -1
Oxygen with fluorine: oxygen is positive
Hydrogen with metals: hydrogen is negative
Set the sum of oxidation states equal to the total charge of the species
Solve for the unknown oxidation state
Check that the result is consistent with known rules and the compound’s overall charge