Nitrogen atom has ________ unpaired electrons, according to __________ rule.

1. Hund's rule: According to Hund's rule of maximum multiplicity, the electron pairing in orbitals of the same energy will not take place until each available orbital of a given subshell is singly occupied.
2. Atomic number of Nitrogen ($\mathrm{N}$) = 7
3. The electronic configuration of the nitrogen ($\mathrm{N}$) atom is $1{\mathrm{s}}^{2}2{\mathrm{s}}^{2}2{\mathrm{p}}^3$.
4. The $2\mathrm{p}$orbital of the nitrogen atom has three sub-levels and each of them consists of one electron. Here pairing will occur only if the fourth electron is added.
5. Therefore nitrogen atom has three unpaired electrons, according to Hund's rule.