Periodic table (electron configurations)

• Configurations of elements 103 and 104 are uncertain; those for elements 105 and above are not available. Predictions from reliable sources have been used for these elements.
• Grayed out electron numbers indicate subshells that are filled to their maximum.
• The bracketed noble gas symbols on the left represent the 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 5p^6p>

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

Uuo, 118, ununoctium : 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 6s² 4f¹⁴ 5d¹⁰ 6p⁶ 7s² 5f¹⁴ 6d¹⁰ 7p⁶

• Note the non-linear shell ordering, which comes about due to the different energies of smaller and larger shells.

References

• Electron configurations of the elements (data page)