# Nitrogen dioxide is a covalent compound. How many oxygen atoms are in a nitrogen dioxide molecule?

Nov 28, 2016

In $N {O}_{2}$? Well I think you can count them yourself.

#### Explanation:

$N {O}_{2}$ is an interesting molecule; because it is a radical species with a formal, lone electron on the central nitrogen:

i.e. $O = {N}^{+} - {O}^{-}$

On the central nitrogen, there are FOUR valence electrons, i.e. there is a nitrogen-centred single electron. That there are 4 valence electrons rather than 5 justifies our distribution of a formal positive charge to this site. Because of this single electron, we can rationalize the formation of ${N}_{2} {O}_{4}$, where the single electrons couple to form a $N - N$ bond:

$2 N {O}_{2} \rightarrow {N}_{2} {O}_{4}$

A Lewis structure of ${\text{^(-)O(O=)N^(+)-}}^{+} N \left(= O\right) {O}^{-}$ is usually invoked.