The electronic configuration of an element with atomic number 7 i.e. nitrogen atom is

${ }_7\mathrm{N}=1{\mathrm{s}}^2,\mathrm{\hspace{0.17em}\hspace{0.17em}}2{\mathrm{s}}^2,\mathrm{\hspace{0.17em}\hspace{0.17em}}2{\mathrm{p}}_{\mathrm{x}}^1\mathrm{\hspace{0.17em}}2{\mathrm{p}}_{\mathrm{y}}^1\mathrm{\hspace{0.17em}}2{\mathrm{p}}_{\mathrm{z}}^1.\mathrm{\hspace{0.17em}}$ Hund's rule states that pairing of electrons in the orbitals of a subshell (orbitals of equal energy) starts when each of them is singly filled.