How many electrons in the nitrite ion, #NO_2^(-)#?
No. of valence electrons:
So around each atom (from left to right above), there are 6, and 5, and 7 valence electrons. Because there are 7 valence electrons around the rightmost oxygen (i.e. 9 electrons in total including the inner shell electrons), this oxygen has a formal negative charge.
Of course there is a resonance isomer:
The neutral nitrogen atom has a formal lone pair in each mesomer.
How would you describe the structure of this ion based on VSEPR?