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117 ununhexiumununseptiumununoctium


Name, Symbol, Number ununseptium, Uus, 117
Chemical series presumably halogens
Group, Period, Block 17, 7, p
Appearance unknown,
probably dark metallic
Standard atomic weight predicted, (310)  g·mol−1
Electron configuration perhaps [Rn] 5f14 6d10 7s2 7p5
(guess based on astatine)
Electrons per shell 2, 8, 18, 32, 32, 18, 7
Phase presumably a solid
CAS registry number 87658-56-8
Selected isotopes
Main article: Isotopes of ununseptium
iso NA half-life DM DE (MeV) DP

Ununseptium (pronounced /ˌjuːnənˈsɛptiəm/) is the temporary name of an undiscovered chemical element in the periodic table that has the temporary symbol Uus and has the atomic number 117. Ununseptium can be referred to as eka-astatine.


The name ununseptium is used as a placeholder, as in scientific articles about the search for element 117. Transuranic elements (those beyond uranium) are, except for microscopic quantities and except for plutonium, 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).

Ununseptium has not yet been discovered. Certain chemical properties, such as bond lengths, are predicted to differ from what one would expect based on periodic trends from the lighter halogens (because of relativistic effects).[1] Ununseptium may show semimetal properties as well.[citation needed] The plans for synthesis of Ununseptium in nearest future exists in Joint Institute for Nuclear Research in Dubna, Russia ([1])


  1. ^ Trond Saue. Principles and Applications of Relativistic Molecular Calculations., page 76
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Ununseptium". A list of authors is available in Wikipedia.
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