Question

What is the oxidation number of nitrogen in the nitrate ion?

Answer 1

The oxidation number of nitrogen in nitrate anion is `+V`.

Explanation:

Oxidation number is the the charge left on the central atom when all the bonding electron pairs are removed with the charge devolving to the most electronegative atom.

Oxygen is more electronegative than nitrogen, hence such an operation will give `O^(2-) xx 3 + ON_N = -1`, where `ON_N` is the oxidation number of nitrogen (and it is understood that the oxidation number of `O` `=` `-II`). Clearly `ON_N = +V`. Of course, as you probably already know, this is a formalism; nitrogen really hasn't lost 5 electrons. We persist teaching these formalisms in order to be to able to balance oxidation/reduction reactions, where such formalisms are quite useful.

What are the oxidation states of nitrogen in ammonia, `NH_3`, `NO_2`, `NO`, and dinitrogen, `N-=N`? Please report your results in this thread.