Question

How do we utilize Lewis structure in simple species such as nitrate ion?

Answer 1

Lewis structure is simply electron counting..........

Explanation:

Let's take the nitrate, anion, `NO_3^(-)`. Nitrogen comes from Group 15, and has five valence electrons, oxygen comes from Group 16, and has six valence electrons.

And thus we have to distribute `5+3xx6+1=24` `"electrons"` around the nitrate core...........Why did I add an extra electron?

And thus, `O=N^(+)(-O^(-))_2`, distributes `6`, `4`, and `2xx7` valence electrons around `O=`, `N`, and `O^-` respectively, and this (with the 2 inner core electrons) accounts for the charge on the atom, neutral, positive, or negative: i.e. `N, Z=7;O, Z=8`.

As always, the charge on the atom is the difference between the nuclear charge, and the electronic charge. For more of the same see [here.](https://socratic.org/questions/what-is-the-formal-charge-of-n-in-hno-3)

What about `NH_3`, and `NH_4^+`?