# What is the Lewis structure for CN_2H_2?

Feb 4, 2015

In order to determine the Lewis structure of methanediimine, or $C {N}_{2} {H}_{2}$, you must first determine the molecule's total number of valence electrons.

This is done by adding the valence electrons of each of the atoms that form the molecule

$4 \cdot \left(1\right) + 2 \cdot \left(5\right) + 2 \cdot \left(1\right) = {\text{16e}}^{-}$

Carbon contributes 4 valence electrons, each of the nitrogen atom acontributes 5, and each of the hydrogen atoms contributes 1 valence electron.

So, start by connecting all the atoms with single bonds.

Each single bond has 2 electrons, so we've used up $4 \cdot 2 = 8$ valence electrons. Now focus on giving the carbon atom a full octet.

Now you only have to work with $4$ valence electrons, since $12$ have been used up already. Give the two nitrogen atoms full octets as well by placing a lone pair of electrons on each atom

This will complete the Lewis structure of the molecule, since all $16$ valence electrons are placed on the molecule.