Some element categories in the periodic table
| Metals | Metalloids | Nonmetals | Unknown chemical properties |
|||||||
| Alkali metals |
Alkaline earth metals |
Inner transition metals | Transition metals |
Post-transition metals |
Other nonmetals |
Halogens | Noble gases |
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| Lanthanides | Actinides | |||||||||
- Configurations of elements 105 and above are uncertain or not available. Predictions from reliable sources have been used for these elements. When no predictions are available, the electron configurations are guessed to be similar to the element directly above them.
- 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 5p6
- 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.
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