How would you draw all of the resonance structures for nitrate?

1 Answer
Dec 22, 2015

By exchanging the electron pairs around the oxygens.

Explanation:

The nitrate ion has three resonance contributors.

i.stack.imgur.com

Nitrate anion possesses 3 formal charges on its atoms.

The nitrogen atom is quaternized (and thus formally positive) in all the representations.

We can consider the double-bonded oxygen to be neutral, and the other oxygens bear formal negative charges; of course, all the oxygen atoms are equivalent by resonance.

We add these 2 negative charges to the formal positive charge on nitrogen and come up with a formal negative charge for the anion, as required.

Of course, all of the #"N-O"# bonds would be the same length (approx. #"1.27 Å"#, compared to an #"N-O"# bond in #"NO"_2#, approx. #"1.20 Å"#, which has a higher bond order.