# What is the Lewis structure of "dinitrogen pentoxide"?

Nitrogen is formally quaternized in ${N}_{2} {O}_{5}$, and each nitrogen bears a formal positive charge.
The central oxygen atom is neutral. There are $2 \times 5 \left(N\right) + 5 \times 6 \left(O\right)$ $=$ $40 \text{ valence electrons" ="20 electron pairs.}$
And thus a Lewis structure of ${\left(O =\right)}^{+} N \left({O}^{-}\right) O \left({O}^{-}\right) {N}^{+} \left(= O\right)$ is reasonable. Clearly, the terminal oxygen atoms are equivalent by resonance. You should practise drawing out the different resonance isomers.