Ununhexium

2007 Schools Wikipedia Selection. Related subjects: Chemical elements

116 ununpentium ← ununhexium → ununseptium Po ↑ Uuh ↓ (Uhh) Periodic Table - Extended Periodic Table
General
Name, Symbol, Number	ununhexium, Uuh, 116
Chemical series	presumably poor metals
Group, Period, Block	16, 7, p
Appearance	unknown, probably silvery white or metallic gray
Atomic mass	(302) g/mol
Electron configuration	perhaps [Rn] 5f14 6d10 7s2 7p4 (guess based on polonium)
Electrons per shell	2, 8, 18, 32, 32, 18, 6
Phase	presumably a solid
CAS registry number	54100-71-9
References

Ununhexium ( IPA: /ˌjuːnʌnˈhɛksiəm/) is the temporary name of a synthetic superheavy element in the periodic table that has the temporary symbol Uuh and has the atomic number 116. Some research has referred to it as " eka-polonium". It is believed to be a brittle metal melting at around 300-400 degrees and vapourising readily.

History

In 1999, researchers at Lawrence Berkeley National Laboratory announced the discovery of elements 116 and 118 (ununhexium and ununoctium), in a paper published in Physical Review Letters. The following year, they published a retraction after other researchers were unable to duplicate the results. In June 2002, the director of the lab announced that the original claim of the discovery of these two elements had been based on data fabricated by the principal author Victor Ninov.

In December, 2000 the Joint Institute for Nuclear Research ( Dubna, Russia) published results that described the discovery in 2000 of decay of the isotope ²⁹²Uuh, which was produced in the reaction of ²⁴⁸Cm with ⁴⁸Ca (curium and calcium, elements 96 and 20, respectively). It has a half-life of about 18 milliseconds (0.018 seconds) and decayed into ²⁸⁸Uuq (ununquadium, element 114). On May 11, 2001, the institute reported synthesizing a second atom, and that the properties confirmed a region of "enhanced" stability (see Island of stability).

In 2004 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).

Ununhexium is a temporary IUPAC systematic element name.

In October, 2006 it was announced that on three occasions californium-249 atoms had been bombarded with calcium-48 ions to produce ununoctium (element 118), which decayed to ununhexium within a millisecond. If confirmed, the synthesis of element 116 will have been proven definitively.