# How do you calculate formal charge of a compound?

A good species to practise on is the nitrate anion, $N {O}_{3}^{-}$, or nitric acid, $H N {O}_{3}$. Nitric acid is a NEUTRAL species; nitrate is anionic. Both species feature formal charge in their Lewis structrures. The neutral nitrogen oxides are also informative for this purpose (cf. $N {O}_{2}$).