To determine the number of lone pairs on nitrogen, we need to consider the electron configuration and molecular structure of ammonia. Nitrogen has five valence electrons, and in ammonia, it forms three covalent bonds with three hydrogen atoms, each sharing one electron. This accounts for three of the nitrogen's five valence electrons.
The remaining two valence electrons on nitrogen are not involved in covalent bonding and form a lone pair. These lone pair electrons occupy an orbital that is not involved in bonding and is localized on the nitrogen atom.
Therefore, there is one lone pair of electrons present on nitrogen in ammonia.
