Untrioctium

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138 Uts ← untrioctium → Ute ↑ Uto ↓ Uoo periodic table - Extended Periodic Table
General
Name, Symbol, Number	untrioctium, Uto, 138
Chemical series
Group, Period, Block	g18, 8, g
Appearance	? Image:.jpg
Atomic mass	? g/mol
Electron configuration
Electrons per shell
Physical properties
Phase	presumably solid
Miscellaneous
Selected isotopes
Main article: Isotopes of untrioctium iso NA half-life DM DE (MeV) DP
References

Untrioctium (IPA: /ʌntrʌɪˈɒktiəm/) is an unsynthesized chemical element with atomic number 138 and symbol Uto.

The name untrioctium is a temporary IUPAC systematic element name.

Contents 1 History 2 Significance 3 External links 4 See also

[edit] History

The name untrioctium is used as a placeholder, as in scientific articles about the search for element 138. Transuranic elements (those beyond uranium) are, except for microscopic quantities, always artificially produced, and usually end up being named for a scientist or the location of a laboratory that does work in atomic physics (see systematic element name for more information).

[edit] Significance

In a non-relativistic approximation, the speed of an electron in a 1s electron orbital, v, is estimated to approach the speed of light for 1s orbitals in element 138. Therefore any element with an atomic number of greater than 138 would require 1s electrons to be traveling faster than c, the speed of light, and as such would not have stable electron orbitals.

The element is the first element with a filled type G electron shell, holding 18 electrons, in its ground state.

[edit] External links

• Feynman Online describes why Uto may be the last element.
• Likely properties of Untrioctium
• Extended Periodic Table

[edit] See also

• Seaborgium
• Eka-Dubnium — Eka-Seaborgium — Eka-Bohrium
• Untriseptium – Untriennium