Oxidation number looks all but a convenient accounting tool for balancing chem equations. Or does it? Why would a molecule care about its oxidation state? Is a different oxidation state sort of a different chem specie with specific properties, reactions, etcetera... Does an oxidation state tend to maintain itself through "weak" exchange processes till some "strong" electron pushing/withdrawing agent gets into? Is it sort of dividing species into carnivores and herbivores?