How many unpaired electrons are in a N atom?

1 Answer
Oct 18, 2016

Well, nitrogen's atomic number is #7#, so it has #5# valence electrons (two in the #2s# orbital and three in the #2p# orbitals) and #2# core electrons (two in the #1s# orbital).

For simple atoms, filling electrons goes in accordance with:

  • The Aufbau principle (lowest to highest energy ordering)
  • Hund's rule (one electron per orbital first, then pair them up after all orbitals for a single energy level are singly occupied)
  • The Pauli Exclusion Principle (opposite spins on the two electrons in each orbital, if there are two; otherwise spin up is the common convention).

Thus, the orbital configuration is (energy increases as you go upwards on this scale):

#ul(uarr color(white)(darr)) " " ul(uarr color(white)(darr)) " " ul(uarr color(white)(darr))#
#underbrace(" "" "" "" "" "" "" "" ")#
#" "" ""2p orbitals"#

#ul(uarr darr)#
#" 2s"#

#ul(uarr darr)#
#" 1s"#

Based on this diagram, how many electrons are unpaired?