Question

What is the oxidation state of nitrogen in hydroxylamine?

Answer 1

The oxidation number of `N` in hydroxylamine, `H_2N-OH`, is `-I`.

Explanation:

By definition, the oxidation number of any atom in a molecule, is the charge left on that atom, when all the bonding pairs of electrons are conceptually broken, with the charge going to the most electronegative atom. Break a `N-H` bond and we get `N^-` and `H^+`. Break a `N-OH` bond and we get `N^+`, and `HO^-`, because oxygen is more electronegative than nitrogen, the oxygen centre gets the electron (please note that this is entirely a conceptual exercise!).

The sum of the individual oxidation numbers must equal the charge on the molecule or the ion. Here, we have a neutral molecule. So `3xxON_H+ ON_O + ON_N` `=` `0`; so `3xx1-2+ON_N = 0`. Thus `ON_N=-I`.

Can you hazard a guess (or a reasoned answer) as to the formal oxidation numbers of nitrogen in ammonia, `NH_3`, and in hydrazine, `H_2N-NH_2`?