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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
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.


Ununseptium has not yet been discovered. As of 2007, no attempt has been made to synthesise this element. The Joint Institute for Nuclear Research in Dubna, Russia has plans for the synthesis of ununseptium in the near future.[1]

The most likely reactions, under discussion, are:

Chemical Properties

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).[2] Ununseptium may show semimetal properties as well.[citation needed]


  1. http://flerovlab.jinr.ru/flnr/flnr/seminars.html
  2. Trond Saue. "Principles and Applications of Relativistic Molecular Calculations" (PDF)., page 76

External links

ar:أنون سيبتيوم ast:Ununseptiu bn:ইউনানসেপটিয়াম be:Унунсептый ca:Ununsepti cs:Ununseptium co:Ununseptiu de:Ununseptium el:Ununseptium eo:Ununseptio fur:Ununseptium ga:Únúinseiptiam gl:Ununseptio (elemento) ko:우눈셉튬 hr:Ununseptij it:Ununseptio he:אונונספטיום sw:Ununsepti la:Ununseptium lb:Ununseptium hu:Ununseptium nl:Ununseptium no:Ununseptium nn:Ununseptium nds:Ununseptium simple:Ununseptium sk:Ununseptium sr:Унунсептијум sh:Ununseptijum fi:Ununseptium sv:Ununseptium th:อูนอูนเซปเทียม uk:Унунсептій