# What is the lewis structure for NO_3^-?

24 valence electrons ($3 \times 6 + 5 + 1$); 3 atoms possess a formal charge.
$O = {N}^{+} {\left(- {O}^{-}\right)}_{2}$ is the standard Lewis structure. Going from left to right, there are 6 electrons around $O$ (hence neutral), 4 electrons around $N$ (hence positive), and 7 electrons around the rightmost oxygens (hence each is a formal anion).
The formal charge can be summed to $- 1$ as required. Of course, the charges are conceived to be delocalized across the structure.