Periodic table (electron configurations)

• Configurations of elements 109 and above are not available. Predictions from reliable sources have been used for these elements.
• <span style="color:gray">Grayed out</span> electron numbers indicate subshells filled to their maximum.
• Bracketed noble gas symbols on the left represent inner configurations that are the same in each period. Written out, these are:

:: He, 2, helium : 1s²

:: Ne, 10, neon : 1s² 2s² 2p⁶

:: Ar, 18, argon : 1s² 2s² 2p⁶ 3s² 3p⁶

:: Kr, 36, krypton : 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶

:: Xe, 54, xenon : 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶

:: Rn, 86, radon : 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 6s² 4f¹⁴ 5d¹⁰ 6p⁶

:: Og, 118, oganesson : 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 6s² 4f¹⁴ 5d¹⁰ 6p⁶ 7s² 5f¹⁴ 6d¹⁰ 7p⁶

• These electron configurations are given for neutral atoms in the gas phase, which are not the same as the electron configurations for the same atoms in chemical environments. In many cases, multiple configurations are within a small range of energies and the small irregularities that arise in the d- and f-blocks are quite irrelevant chemically. The construction of the periodic table ignores these irregularities and is based on ideal electron configurations.
• The shells do not fill in simple shell-number order, which comes about due to the different energies of smaller and larger shells and subshells. The filling order is approximately described by the Madelung rule.

See also

• Electron configurations of the elements (data page)

References

See list of sources at Electron configurations of the elements (data page).