# Ununhexium

 116 ununpentium ← ununhexium → ununseptium Po↑Uuh↓(Uhh)
General
Name, Symbol, Number ununhexium, Uuh, 116
Chemical series presumably poor metals
Group, Period, Block 16, 7, p
Standard atomic weight (293)  g·mol−1
Electron configuration perhaps [Rn] 5f14 6d10 7s2 7p4
(guess based on polonium)
Electrons per shell 2, 8, 18, 32, 32, 18, 6
CAS registry number 54100-71-9
Selected isotopes
iso NA half-life DM DE (MeV) DP
293Uuh syn 61 ms alpha 10.54 289Uuq
292Uuh syn 18 ms alpha 10.66 288Uuq
291Uuh syn 18 ms alpha 10.74 287Uuq
290Uuh syn 7.1 ms alpha 10.84 286Uuq
References

Ununhexium (pronounced /ˌjuːnənˈhɛksiəm/) 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".

## Discovery

On July 19, 2000, scientists at Dubna (FLNR) detected a single decay from an atom of ununhexium following the irradiation of a Cm-248 target with Ca-48 ions. The results were published in December, 2000.[1]. This 10.54 MeV alpha-emitting activity was originally assigned to 292Uuh due to the correlation of the daughter to previously assigned 288Uuq. However, that assignment was later altered to 289Uuq, and hence this activity was correspondingly changed to 293Uuh. Two further atoms were reported by the institute during their second experiment between April-May 2001.

${\displaystyle \,_{20}^{48}\mathrm {Ca} +\,_{96}^{248}\mathrm {Cm} \to \,_{116}^{296}\mathrm {Uuh} ^{*}\to \,_{116}^{293}\mathrm {Uuh} +3\,_{0}^{1}\mathrm {n} }$

In the same experiment they also detected a decay chain which corresponded to the first observed decay of ununquadium and assigned to 289Uuq. This activity has not been observed again in a repeat of the same reaction. However, its detection in this series of experiments indicates the possibility of the decay of meta-stable isomer of ununhexium, namely 293m116, or a rare decay branch of the already discovered ground state isomer, in which the first alpha particle was missed. Further research is required to positively assign this activity.

## Synthesis of Other Isotopes

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.[2] If confirmed, the synthesis of element 116 will have been proven definitively.

The reaction that created ununhexium is:

${\displaystyle \,_{96}^{248}\mathrm {Cm} +\,_{20}^{48}\mathrm {Ca} \,\to \,_{116}^{292}\mathrm {Uuh} +4\;_{0}^{1}\mathrm {n} \;}$

This decayed 47 milliseconds later as follows to a previously identified isotope of element 114, Uuq.

${\displaystyle \,_{116}^{292}\mathrm {Uuh} \to \,_{114}^{288}\mathrm {Uuq} \,+\,_{2}^{4}\mathrm {He} \;}$
File:Ununoctium-294 nuclear.png
One of the isotopes of 116 is formed through the decomposition of Uuo

## Proposed Name

Ununhexium is a temporary IUPAC systematic element name. It is rumoured that scientists from the Flerov Laboratory of Nuclear Reactions (FLNR) have proposed the name Flyorovium (Fl) for ununquadium, in honour of G. N. Flyorov, head of the group that synthesized elements 102 to 110. However, there is no evidence in the public domain of such a proposition. It should be noted that the name Flerovium has been previously used by the group for element 102 during the period of controversy over the naming of elements 101-109, before the name Nobelium was accepted.[3] Given that the name was not used (widely) in publications, the name Flerovium is not banned by IUPAC according to their current naming rules, although this may explain the alternative spelling. It should be stated that the JWP is currently assessing the validity of the claim of discovery by the group and should publish their findings this year. Only then will the team be invited to propose a name. It should also be said that the use of Fl as a new chemical symbol is highly unlikely due to confusion with Fluorine (F).

## 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.[4] The following year, they published a retraction after other researchers were unable to duplicate the results.[5] 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.

## References

1. Oganessian, Yu. Ts. (2000). "Observation of the decay of 292116". Physical Review C. 63: 011301. doi:10.1103/PhysRevC.63.011301. Unknown parameter |coauthors= ignored (help)
2. Oganessian, Yu. Ts. (2006). "Synthesis of the isotopes of elements 118 and 116 in the 249Cf and 245Cm+48Ca fusion reactions". Physical Review C. 74: 044602. doi:10.1103/PhysRevC.74.044602. Unknown parameter |coauthors= ignored (help)
3. Ninov, V. (1999). "Observation of Superheavy Nuclei Produced in the Reaction of 86Kr with 208Pb". Physical Review Letters. 83: 1104. doi:10.1103/PhysRevLett.83.1104. Unknown parameter |coauthors= ignored (help)