Ununoctium

Ununoctium is the temporary IUPAC name for the superheavy element having atomic number of 118, currently the highest atomic number assigned to a reputedly discovered element. It has the temporary IUPAC element symbol Uuo. Ununoctium probably shares similar properties of its group, the noble gases, resembling radon in its chemical proerties, and so some some researchers have referred to it as aka-radon. It is probably the second radioactive gaseous element and the first standard semiconcuctive gas. Ignoring nuclear instability due to radioactivity, scientists expect that ununoctium is much more chemically reactive than xenon or radon. It would likely form stable oxides (UuoO₃, etc.) as well as chlorides and fluorides. The name ununoctium is a systematic element name, used as a placholder until the IUPAC decides on a name. On October 9, 2006, researchers working at the Joint Institute for Nuclear Research (JINR) in Dubna, Russia, announced in Physical Review C that they had indirectly detected a total of three nuclei of ununoctium-294 (one in 2002 and two more in 2005) produced via collisions of californium-249 atoms and calcium-48 ions:	2 He 4.002
	10 Ne 20.17
	18 Ar 39.94
	36 Kr 83.80
	54 Xe 131.3
	86 Rn 222.0
	118 Uuo 293.0

Because of the very small fusion reaction probability (the fusion cross section is 0.5 pb = 5×10^-41 m²) more than 4×10¹⁹ calium ions had to be shot at the californium to have only three fusion reactions.

The research team consisted of workers from JINR and the Lawrence Livermore National Laboratory in California, USA. The decay products of three atoms of ununoctium, not the atoms themselves, were observed in Dubna. A half-life of 0.89 ms was observed: ²⁹⁴Uuo decays into ²⁹⁰Uuh by alpha decay.

The identification of the ²⁹⁴Uuo nuclei was verified by separately creating the putative daughter nucleus ²⁹⁰Uuh by means of a bombardment of ²⁴⁵Cm with ⁴⁸Ca ions,

and checking that the ²⁹⁰Uuh decay matched the decay chain of the ²⁹⁴Uuo nuclei.

The daughter nucleus ²⁹⁰Uuh is very unstable, decaying with a half-life of 14 milliseconds into ²⁸⁶Uuq, which may undergo spontaneous fission or undergo alpha decay into ²⁸²Uub, which will undergo spontaneous fission.

In 1999, researchers at Lawrence Berkeley National Laboratory had announced the discovery of elements 116 and 118, 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 principal author Victor Ninov.

The American group had intended to name it ghiorsium after Albert Ghiorso before having to retract their claim.

In 1999, the team at Lawrence Berkley Labs published a paper in the journal Physical Review Papers proclaiming their discovery of element 118. The scientific community exploded, hoping that the decay time of 118 (eka-radon) would longer than that of 114. Element 116 was also synthesized during this reaction, which used cold fusion to fuse ¹⁰⁸Pb and ⁸⁶Kr atoms together.

However, this experiment has NOT been repeated successfully at other laboratories. Lawrence Berkley Labs officially retracted their paper in 2001, saying that they had actually misinterpreted their data. Despite this, efforts to produce element 118 have not halted, and element 118 may yet still be synthesized.

1s²
2s²	2p⁶
3s²	3p⁶	3d¹⁰
4s²	4p⁶	4d¹⁰	4f¹⁴
5s²	5p⁶	5d¹⁰	5f¹⁴
6s²	6p⁶	6d¹⁰
7s²	7p⁶

Isotope	Atomic Mass	Half-Life
²⁹³Uuo	293.21467
²⁹⁴Uuo