What does the superscript represent in electron configuration notation?

1 Answer
Truong-Son N.
Oct 30, 2016

The superscript represents the number of electrons in that particular orbital sublevel (it does not represent an element inside an orbital).

For example,

#1s^color(red)(2) 2s^color(red)(2) 2p^color(red)(5)# tells us that there are:

  • #2# electrons in the core #1s# orbital of #"F"#
  • #2# electrons in the core #2s# orbital of #"F"#
  • #5# total electrons combined in the #2p_x#, #2p_y#, and #2p_z# valence orbitals of #"F"#.

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

#ul(uarrdarr)#
#""# #2s#
#" "#
#" "#
#" "#
#" "#
#" "#
#" "#
#" "#
#" "#
#ul(uarrdarr)#
#""# #1s#

The total number of electrons tells us that for a neutral element, the atomic number is equal to that number, telling us the identity of the element in question (assuming neutrality).

Thus, I knew it was #"F"# if I assumed it was neutral and found that obviously, #2 + 2 + 5 = 9#, as this is the atomic number of #"F"#.

(Of course, it could have also been #"O"^(-)#, or #"Ne"^(+)#, but those are significantly less realistic.)

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