Question #5f272

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Stefan V.
Mar 17, 2015

Nitrogen dioxide, or NO_2, is an odd-electron molecule, i.e. the number of valence electrons the molecule has is not an even number.

More specifically, nitrogen dioxide has a total of 17 valence electrons - 5 from nitrogen and 6 from each of the two oxygen atoms that comprise the molecule.

Now, VSEPR Theory can be extended to accomodate odd-electron molecules. In this case, the nitrogen dioxide molecule is considered to have a AX_2E_0.5 geometry, which is right between AX_2E_0 - linear, and AX_2E_1 - bent.

http://www.elmhurst.edu/~chm/vchembook/206bent.html

The molecule's geometry will still be closer to bent, but the bond angle will be larger than the ideal 120^@ such a geometry predicts, mostly because the oxygen atoms experience less repulsion from the single electron present on the nitrogen atom.

The actual bond angle for nitrogen dioxide is 134^@. By comparison, the angle found in the nitrite ion, or NO_2^(-), is 115.4^@, because now nitrogen has attached a full lone pair of electrons that experience greater repulsion with the oxygen atoms.

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