# Using the Lewis electron dot structure for NO_3^-, what is the total number of non-shared electrons?

$\left(O =\right) {N}^{+} {\left(- O\right)}_{2}^{-}$ is the typical resonance isomer. Such a structure demands that the doubly bound oxygen has 2 lone pairs, and each of the singly bound oxygen have 3 lone pairs.
Because there are 7 valence electrons around each singly bound oxygen atom, these atoms have a formal negative charge. To balance this $- 2$ charge, the quaternized nitrogen, which has 4 valence electrons, has a formal $+ 1$ charge. This is entirely consistent with the ionic charge of the nitrate ion. Why?