Is the nonbonding orbital of NH3 a p orbital?

1 Answer
Sep 2, 2017

MOSTLY true. The lone pair is in a molecular orbital that is similar to a p orbital because it has significant p orbital characteristics, but it is not in a pure p atomic orbital.


Consider this orbital diagram of NH3:

![http://www.chemtube3d.com/](useruploads.socratic.org)

In a sense, I suppose the lone pair is in a p-like orbital... How we label it depends on how we treat the atomic orbitals.

  • In a hybridized treatment, one would place the nitrogen lone pair in an sp3 orbital, as seen in the above diagram. In this case, all four orbitals nitrogen uses for bonding are identical, with 75% p character and 25% s character.
  • In an unhybridized treatment, one would place the nitrogen lone pair in a molecular orbital with significant p characteristics, and the molecular orbital would primarily belong to the nitrogen.

![www.ch.ic.ac.uk)

And in the above molecular orbital diagram, I would be referring to the molecular orbital labeled 2a1, which you can see involves interactions between more than one orbital.

Therefore, it is not a pure, nonbonding atomic orbital.

Either approach leads to the conclusion that the orbital contains significant p orbital characteristics, but it is not in a pure p orbital because it is not a purely nonbonding orbital.