Purpose of Oxidation Numbers [ENDORSED]

[Nick Smith 2H]

What role do oxidation numbers play? Are they only useful when dealing with metalloids in coordination compounds? It's a little unclear to me where to use oxidation numbers instead of the charge of an atom.

[Chem_Mod]

Oxidation numbers allow for electron “book-keeping”. In contrast to formal charge, oxidation states take the electronegativity of atoms into consideration, representing that electrons are not always shared equally. Whereas formal charge considers electrons between atoms to be shared equally. This is important when we are trying to predict structure, but formal charge is not always enough.

The most useful situation where we use oxidation states are in redox reactions. The oxidation states help us keep track of what’s being oxidized and what is being reduced. This being said, most metal reactions that we learn about in this course are redox reactions, so we use formal charge especially for those metal reactions.