# What is the molecular geometry of the NO_3^– ion?

There are $3 \times 6 + 5 + 1 = 24$ valence electrons. A Lewis structure of $\left(O =\right) {N}^{+} {\left(- O\right)}_{2}^{-}$ is reasonable. Because there are 3 regions of electron density around the central nitrogen, trigonal planar geometry is suggested.
Note that in the given Lewis structure, 3 of the 4 atoms bears a formal charge. The sum of the formal charges: $+ 1 - 1 - 1$ is the charge on the ion.