[ General Glossary, Quantum Glossary, Atomic Glossary ]
Electron (Subshell) Configurations

The configuration of the N equivalent electrons in a given subshell is usually written as
n lN
where

  • n is the principal quantum number (a positive integer, as above)
  • l is a letter used to specify the value of the orbital angular momentum quantum number (which has allowed values l = 0, 1, ..., n-1)
    value of l 0 1 2 3 4 5 6 7 8
    letter code for l s p d f g h i k l
The superscript value for N is often omitted if N=1.
Examples:
  • the configuration 2p3
    • n=2 (this subshell is part of the ion's L-shell)
      • (the ion's L-shell also has a 2s subshell)
    • l=1
    • N=3 (3 equivalent electrons)
      • Note this subshell is "unfilled", "open" or "incomplete", since a "full" subshell case the maximum number of electrons (2(2l+1)) which in this case (l=1) is 6.
  • the configuration 3p6
    • n=3 (this subshell is part of the ion's M-shell)
    • l=1
    • N=6 (6 equivalent electrons)
      • Note this subshell is therefore a "full".
The combined configuration of several subshells is specified by combining the notation of the individual subshells:
Examples:
  • the configuration 3s2 3p6 3d10
    • 3 subshells of the ion's (n=3) M-shell)
      • (all of which are "full" since for each N = 2(2l+1))
The parity of a configuration can be Odd or Even depending upon whether SUMi li is Odd or Even.