 The stabilization of the 7s electrons is called the inert pair effect; the effect that separates the 7p subshell into the more-stabilized and the less-stabilized parts is called subshell splitting.Computational chemists understand the split as a change of the second (azimuthal) quantum number "l" from 1 to 1/2 and 3/2 for the more-stabilized and less-stabilized parts of the 7p subshell, respectively.For many theoretical purposes, the valence electron configuration may be represented to reflect the 7p subshell split as .