# What is the charge, and Lewis structure of the nitrate anion?

The nitrate ion, $N {O}_{3}^{-}$, has a SINGLE, FORMAL negative charge.
The sum of the individual oxidation numbers will be the charge on the ion. We thus have ${N}^{V +} + 3 \times {O}^{- I I} = - I$ as required. Note that Lewis structure of nitrate anion shows formal charge on THREE of the FOUR participating atoms: a positive charge on the central (quaternized) nitrogen atom, and negative charges on TWO of the oxygen atoms.
The Lewis structure is usually depicted as $\left(O =\right) \stackrel{+}{N} {\left(- {O}^{-}\right)}_{2}$, which bears a formal negative charge as required.