Hund's rule states that within a subshell, electrons

  • A. pair up in the lowest orbital first
  • B. occupy separate orbitals singly with parallel spins before any pairing occurs
  • C. always have opposite spins
  • D. fill the highest energy orbital first

Explanation

Spreading out into empty orbitals minimises electron electron repulsion, so nitrogen's three 2p electrons occupy the three separate p orbitals rather than crowding two into one. This is why so many transition metal ions are paramagnetic. Pairing only begins once every orbital in the subshell holds one electron.

Related questions