Electron configurations of the elements (data page)

This page shows the electron configurations of the neutral gaseous atoms in their ground states. For each atom the subshells are given first in concise form, then with all subshells written out, followed by the number of electrons per shell. Electron configurations of elements beyond hassium (element 108) are predicted.

As an approximate rule, electron configurations are given by the Aufbau principle and the Madelung rule. However there are numerous exceptions; for example the lightest exception is chromium, which would be predicted to have the configuration 1s²2s²2p⁶3s²3p⁶3d⁴4s², written as [Ar]3d⁴4s², but whose actual configuration given in the table below is [Ar]3d⁵4s¹.