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115 ununquadiumununpentiumununhexium


Name, Symbol, Number ununpentium, Uup, 115
Group, Period, Block 15, 7, p
Standard atomic weight (299)  g·mol−1
Electron configuration perhaps [Rn] 5f14 6d10 7s2 7p3
(guess based on bismuth)
Electrons per shell 2, 8, 18, 32, 32, 18, 5
CAS registry number 54085-64-2
Selected isotopes
Main article: Isotopes of ununpentium
iso NA half-life DM DE (MeV) DP
288Uup syn 87 ms

Ununpentium (pronounced /juːnənˈpɛntiəm/) is the temporary name of a synthetic superheavy element in the periodic table that has the temporary symbol Uup and has the atomic number 115. Multiple isotopes have been made by a fusion of calcium and americium (Uup-288 with the most neutrons). It can be referred to as eka-bismuth.

Element 115 also falls in the center of the theoretical island of stability. Although no stable isotopes have yet been found, conventional models predict that if stable isotopes of element 115 can be produced, they will most likely need the "magic number" of 184 neutrons, which would be Uup-299. The currently fabricated isotopes only had at most 173 neutrons (Uup-288).



On February 2, 2004, synthesis of ununpentium and ununtrium were reported in Physical Review C by a team composed of Russian scientists at Dubna University's Joint Institute for Nuclear Research and American scientists at the Lawrence Livermore National Laboratory.[1][2]

The team reported that they bombarded americium (element 95) with calcium (element 20) to produce four atoms of ununpentium (element 115). These atoms, they report, alpha decayed to ununtrium (element 113) in approximately 100 milliseconds. The ununtrium produced then existed for 1.2 seconds before decaying into natural elements.

The synthesizing of the element was also reported by scientists of Japan.

In May 2006 in the Joint Institute for Nuclear Research the synthesis of this element was confirmed by another method (the chemical identifying on final products of decay of element).

Ununpentium is a temporary IUPAC systematic element name. Element 115 is also sometimes called eka-bismuth.

Chemical properties

For now element 115 has only been manufactured in the amount of a few atoms, so the chemistry of element 115 has yet to be researched, but chemistry and physics can tell us a lot about what to expect. Although element 115 is in the same group as bismuth, its chemistry will probably be strongly altered by relativistic effects.[3] One important predicted difference from bismuth is the presence of a stable oxidation state of +1, and a Uup+ ion with a chemistry similar to Tl+. There has been some experimental data for other superheavy elements, such as element 112, which seems to confirm relativistic effects for superheavy elements.

In popular culture

Ununpentium has been theorized to be inside the island of stability. This probably explains why it was mentioned regularly in popular culture, especially in UFO conspiracy theories. The most popular account of element 115, from Bob Lazar, would require changes to a great many existing theories.[4]

See also


  1. ^ Oganessian, Yu. Ts.; et al. (2004). "Experiments on the synthesis of element 115 in the reaction 243Am(48Ca,xn)291−x115". Physical Review C 69: 021601. doi:10.1103/PhysRevC.69.021601.
  2. ^ Oganessian, Yu. Ts.; et al. (2005). "Synthesis of elements 115 and 113 in the reaction 243Am + 48Ca". Physical Review C 72: 034611. doi:10.1103/PhysRevC.72.034611.
  3. ^ Keller, O. L., Jr.; C. W. Nestor, Jr. (1974). "Predicted properties of the superheavy elements. III. Element 115, Eka-bismuth". Journal of Physical Chemistry 78: 1945. doi:10.1021/j100612a015.
  4. ^ David L. Morgan (August 26, 1996, revised October 2005). Lazar Critique. Retrieved on 2007-08-18.
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Ununpentium". A list of authors is available in Wikipedia.
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