Density Difference Colorizations for Diatomic Nitrogen

Note: The colorizations below are 2-dimensional images. The blue and purple areas represent an increased electron density, while the yellow and green areas represent a decreased electron density. The centers of each of these sections are the areas of greatest magnitude. Remember, when one says that the electron density increased or decreased in a specific area, that is with respect to the electron density of the non-interacting atoms.

This first image involves the electron density of only the p_sigma electrons, one from each atom. The blue and purple areas represent the sigma bond.

The above image includes only the electron density of the 4 p_pi electrons, two from each atom. First, it is significant that the blue areas do not include any purple as the sigma bond did. This is because the two p_pi bonds are not as strong as the sigma bonds. The p_pi orbitals of each atom do not approach each other head on as the p_sigma orbitals do. Therefore, the p_sigma orbitals "see" each other first, and are closer throughout the interaction between the two atoms.

The above image involves the electron density of the two lone pairs. Notice how their densities are completely concentrated to the outside of the molecule. This would be expected because the lone pairs are repelled by the bonding electrons.

This final image incorporates all 14 of the molecule's electrons. It is difficult to distinguish what exactly is happening with this image alone, but after viewing the previous images the meaning of this total electron density distribution should be clear.

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