What is the Lewis structure for #CN_2H_2#?

1 Answer
Feb 4, 2015

In order to determine the Lewis structure of methanediimine, or #CN_2H_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 * (1) + 2 * (5) + 2 * (1) = "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 * 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.