View source for Ununoctium

{{Elementbox_header | number=118 | symbol=Uuo | name=ununoctium | left=[[ununseptium]] | right=[[ununennium]] | above=[[radon|Rn]] | below=(Uho) | color1=#ecfefc | color2=gray }}
{{Elementbox_series | [[noble gas]]es }}
{{Elementbox_groupperiodblock | group=18 | period=7 | block=p }}
{{Elementbox_appearance | unknown, probably colorless<ref name="webelements">{{citeweb|url=http://www.webelements.com/webelements/elements/text/Uuo/key.html|title=Ununoctium|publisher=WebElements Periodic Table|accessdate=2007-12-09}}</ref> }}
{{Elementbox_atomicmass_gpm |(predicted) [[1 E-25 kg|(314)]]<ref name="apsidium">{{citeweb|url=http://www.apsidium.com/elements/118.htm|title=Apsidium on Ununoctium  -  Moskowium|date=2007-12-03|accessdate=2007-12-08}}</ref>}}
{{Elementbox_econfig | perhaps &#91;[[radon|Rn]]&#93; 7s<sup>2</sup> 5f<sup>14</sup> 6d<sup>10</sup> 7p<sup>6</sup><ref name="electronic">{{citeweb|title=Ununoctium: Electronic Configuration|publisher=WebElements Periodic Table|url=http://www.webelements.com/webelements/elements/text/Uuo/econ.html|accessdate=2007-12-08}}</ref>}}
{{Elementbox_epershell | 2, 8, 18, 32, 32, 18, 8 <ref name="electronic"/>}}
{{Elementbox_phase | expected to be a [[gas]]<ref name="webelements"/>}}
{{Elementbox_density_gpcm3nrt|(predicted) (13.65)<ref name="apsidium"/>}}
{{Elementbox_meltingpoint|k=(243)<ref name="apsidium"/> (predicted)|c=(-30.3)| f= }}
{{Elementbox_boilingpoint|k=(250)<ref name="apsidium"/> (predicted)|c=(-22.6)| f=}}
{{Elementbox_oxistates| '''0''' <ref name="compounds"/>}}
{{Elementbox_electroneg_pauling | ''no data''}}
{{Elementbox_ionizationenergies1|(predicted) (963)<ref name="apsidium"/>}}
{{Elementbox_atomicradiuscalc_pm|[[1 E-10 m|152]]<ref name="apsidium"/>}}
{{Elementbox_thermalcond_wpmkat300k|(0.001807)<ref name="apsidium"/>}}
{{Elementbox_cas_number | 54144-19-3<ref name="webelements"/>}}
{{Elementbox_isotopes_begin | color1=#ecfefc | color2=gray }}
{{Elementbox_isotopes_decay | mn=294| sym=Uuo <ref name="full"/>| na=[[synthetic radioisotope|syn]] | hl= ~0.89 ms| dm= [[alpha decay|α]]| de= 11.65 ± 0.06| pn= 290| ps= [[Uuh]]}}
{{Elementbox_isotopes_end}}
{{Elementbox_footer | color1=#ecfefc | color2=gray}}
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Ionization energy (eV) < 9.9599 > 
Molar Volume   cm 3 < 62.58 > 
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'''Ununoctium''' ({{pronEng|ˌjuːnəˈnɒktiəm}} <ref>{{citeweb|url=http://reference.aol.com/columbia/_a/ununoctium/20051207161909990012|quote=Pronounced yoo'nànŏk`tēàm|title=Columbia Encyclopedia on ununoctium|accessdate=2007-12-08}}</ref><ref>{{citeweb|url=http://education.jlab.org/itselemental/ele118.html|title=It's Elemental: Ununoctium|quote=Ununoctium is pronounced as oon-oon-OCT-i-em|accessdate=2007-12-08}}</ref>) is the temporary [[International Union of Pure and Applied Chemistry|IUPAC]] name for the [[transactinide element]] having [[atomic number]] of 118. It can also be referred to as '''[[Mendeleev's predicted elements|eka]]-[[radon]]''' and it is currently the only [[synthetic element|synthetic]] member of the [[noble gas]]es group, and the highest atomic number assigned to a reputedly discovered element. Its temporary IUPAC [[chemical symbol|element symbol]] is '''Uuo'''. Only three atoms of this element have been detected.<ref>{{citeweb|url=http://discovermagazine.com/2007/jan/physics/article_view?b_start:int=1&-C=|title=The Top 6 Physics Stories of 2006|accessdate=2007-12-08|author=Stone, Alex|date=2007-01-07|publisher=Discover Magazine}}</ref> The name ''ununoctium'' is a [[systematic element name]], used as a [[Placeholder name|placeholder]] until it will be confirmed by other research groups and the [[IUPAC]] decides on a name. ''Moskowium (Mk)'' has been proposed by their Russian discoverers as the permanent name for the element.<ref>{{ru icon}}{{citeweb|language=russian|author=NewsInfo|date=2006-10-17|url=http://www.rambler.ru/news/science/0/8914394.html|title=Periodic table has expanded|publisher=Rambler|accessdate=2007-12-09|lang=ru}}</ref><ref>{{ru icon}}{{citeweb|last=Yemel'yanova|first=Asya|date=2006-12-17|url=http://www.vesti.ru/doc.html?id=113947|title=118th element will be named in Russian|publisher=vesti.ru|accessdate=2007-12-09|lang=ru}}</ref>

==Isolation==
===Unsuccessful attempts===
In late [[1998]], the Polish theoreticist Robert Smolanczuk published some calculations on the fusion of atomic nuclei towards the synthesis of superheavy atoms, including the element 118.<ref>{{citejournal|url=http://prola.aps.org/abstract/PRC/v59/i5/p2634_1|author=Robert Smolanczuk|journal=[[Physical Review]] C|colume=59|issue=5|year=1999|month=05|title=Production mechanism of superheavy nuclei in cold fusion reactions|pages=2634 - 2639|accessdate=2007-12-08}}</ref> His calculations suggested that it might be possible to make element 118 by fusing [[lead]] with [[krypton]] under carefully controlled conditions.<ref>{{citeweb|title=Ununoctium: Historical Information|publisher=WebElements Periodic Table|url=http://www.webelements.com/webelements/elements/text/Uuo/hist.html|accessdate=2007-12-08}}</ref>

In [[1999]], researchers at [[Lawrence Berkeley National Laboratory]] made use of these predictions and announced the discovery of elements [[Ununhexium|116]] and 118, in a paper published in ''[[Physical Review Letters]]'',<ref>{{citejournal|last = Ninov|first = Viktor|coauthors = K. E. Gregorich, W. Loveland, A. Ghiorso, D. C. Hoffman, D. M. Lee, H. Nitsche, W. J. Swiatecki, U. W. Kirbach, C. A. Laue, J. L. Adams, J. B. Patin, D. A. Shaughnessy, D. A. Strellis, and P. A. Wilk|title = Observation of Superheavy Nuclei Produced in the Reaction of <sup>86</sup>Kr with <sup>208</sup>Pb|journal = [[Physical Review Letters]]
|volume = 83|issue = 6-9|pages = 1104–1107|date = 1999-05-27|url = http://prola.aps.org/abstract/PRL/v83/i6/p1104_1?qid=a064607e43de02b9&qseq=1&show=25|doi = 10.1103/PhysRevLett.83.1104|accessdate=2007-12-08}}</ref> and very soon after the results were reported in ''[[Science (journal)|Science]]''.<ref>{{citejournal|author=Robert F. Service|journal=Science|date=1999-06-11|volume=284|number=5421|pages=1751|doi=10.1126/science.284.5421.1751|title=Berkeley Crew Bags Element 118|url=http://sciencenow.sciencemag.org/cgi/content/full/1999/607/1|accessdate=2007-12-08}}</ref> The researchers claimed to have performed the reaction:
:<math>\,^{86}_{36}\mathrm{Kr} + \,^{208}_{82}\mathrm{Pb} \, \to \,^{293}_{118}\mathrm{Uuo} + \,^{1}_{0}\mathrm{n} \; </math>

The following year, they published a retraction after other researchers were unable to duplicate the results.<ref>{{citenews|url=http://enews.lbl.gov/Science-Articles/Archive/118-retraction.html|publisher=Berkeley Lab|author=Public Affairs Department |title=Results of element 118 experiment retracted|date=2001-07-21|accessdate=2007-12-08}}</ref>
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]].<ref>{{citejournal|first=Dalton|last=Rex|date=2002-12-19|pages=728-729|title=Misconduct: The stars who fell to Earth|url=http://www.nature.com/nature/journal/v420/n6917/full/420728a.html|journal=[[Nature (journal)|''Nature'']]|volume=420|doi=10.1038/420728a}}</ref>  The American group had intended to name it ''ghiorsium'' after [[Albert Ghiorso]] (a member of the research team) before having to retract their claim.<ref>{{citeweb|title=Discovery of New Elements Makes Front Page News|url=http://www.lbl.gov/Science-Articles/Research-Review/Magazine/1999/departments/breaking_news.shtml|publisher=Berkeley Lab Research Review Summer 1999|year=1999|accessdate=2007-12-08}}</ref>

===Discovery ===
On [[October 16]], [[2006]], researchers from [[Joint Institute for Nuclear Research]] (JINR) and [[Lawrence Livermore National Laboratory]] of California, USA, working at the 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<ref>{{citeweb|url=http://159.93.28.88/linkc/118/anno.html|title=Element 118: results from the first <sup>249</sup>Cf + <sup>48</sup>Ca experiment|author=Oganessian Yu.Ts. et al.|year=2002|publisher+JINR Publishing Department|accessdate=2007-12-08}}</ref> and two more in 2005) produced via collisions of [[californium]]-249 atoms and [[calcium-48]] ions:<ref>{{citeweb|url=http://www.llnl.gov/pao/news/news_releases/2006/NR-06-10-03.html|title=Livermore press release about discovery|date=2006-12-03|accessdate=2007-12-08}}</ref><ref>{{citejournal|author=Yu. Ts. Oganessian|title=Synthesis and decay properties of superheavy elements|journal=Pure Appl. Chem.|volume=78|pages=889-904|url=http://www.apsidium.com/elements/iupac_oganessian_2006.pdf|doi=10.1351/pac200678050889|date=2006-08-01}}</ref><ref>{{citeweb|last=Sanderson|first=Katherine|title=Heaviest element made - again|work=nature@news.com|publisher=[[Nature (journal)]]|date=2006-10-17|url=http://www.nature.com/news/2006/061016/full/061016-4.html|accessdate=2007-12-08}}</ref><ref>{{citeweb|author=Phil Schewe|coauthor=Ben Stein|title=Elements 116 and 118 Are Discovered|work=Physics News Update|publisher=[[American Institute of Physics]]|date=2006-10-17|url=http://www.aip.org/pnu/2006/797.html|accessdate=2007-12-08}}</ref><ref>{{citeweb|url=http://www.washingtonpost.com/wp-dyn/content/article/2006/10/16/AR2006101601083.html|title=Scientists Announce Creation of Atomic Element, the Heaviest Yet|publisher=[[Washington Post]]|author=Rick Weiss|date=2006-10-17|accessdate=2007-12-08}}</ref>

:<math>\,^{249}_{98}\mathrm{Cf} + \,^{48}_{20}\mathrm{Ca} \, \to \,{}^{294}_{118}\mathrm{Uuo} + 3 \; ^1_0\mathrm{n} \; </math>
[[Image:Ununoctium-294_nuclear.png‎|thumb|left|200px|[[Radioactive decay]] pathway of [[isotope]] Uuo-294.<ref name="full"/> The [[decay energy]] and average [[half-life]] is given for the [[parent isotope]] and each [[daughter isotope]]s. The fraction of atoms undergoing [[spontaneous fission]] (SF) is given in green.]]

Because of the very small fusion reaction probability (the fusion [[Nuclear cross section|cross section]] is 0.5 pb = 5×10<sup>−41</sup> m<sup>2</sup>) the experiment took 4 months and involved a beam of 4×10<sup>19</sup> [[calcium]] ions that had to be shot at the [[californium]] target to produce the single recorded event believed to be the synthesis of the element 118.<ref name="webelements"/>  Nevertheless, researchers are highly confident that the result is not a false positive, since the chance that the detection was a random event was estimated to be less than one part in 100,000.<ref>{{citeweb|quote="I would say we're very confident."|url=http://pubs.acs.org/cen/news/84/i43/8443element118.html|title=Element 118 Detected, With Confidence|publisher=Chemical and Engineering news|date=2006-10-17|accessdate=2007-12-09}}</ref> 

In the experiment, the decay products of three atoms of ununoctium, rather than the atoms themselves, were observed. A [[half-life]] of 0.89 ms was observed: <sup>294</sup>Uuo decays into <sup>290</sup>[[Ununhexium|Uuh]] by [[alpha decay]]. Since there were only three nuclei, the half-life was derived from observed lifetimes and has a large uncertainty: 0.89<sub>-0.31</sub><sup>+1.07</sup> ms.<ref name="full"/>

:<math>\,^{294}_{118}\mathrm{Uuo} \to \,{}^{290}_{116}\mathrm{Uuh} + \; ^4_2\mathrm{He} \; </math>

The identification of the <sup>294</sup>Uuo nuclei was verified by separately creating the putative daughter nucleus <sup>290</sup>Uuh by means of a bombardment of <sup>245</sup>[[Curium|Cm]] with <sup>48</sup>[[calcium|Ca]] ions,

:<math>\,^{245}_{96}\mathrm{Cm} + \,^{48}_{20}\mathrm{Ca} \, \to \,^{290}_{116}\mathrm{Uuh} + 3 \; ^1_0\mathrm{n} \; </math>

and checking that the <sup>290</sup>Uuh decay matched the decay chain of the <sup>294</sup>Uuo nuclei.<ref name="full"/>  The daughter nucleus <sup>290</sup>Uuh is very unstable, decaying with a half-life of 14 milliseconds into <sup>286</sup>[[Ununquadium|Uuq]], which may undergo [[spontaneous fission]] or alpha decay into <sup>282</sup>[[Ununbium|Uub]], which will undergo spontaneous fission.<ref name="full">{{citejournal|last = Oganessian|first = Yu. Ts.
|coauthors = Utyonkov, V.K.; Lobanov, Yu.V.; Abdullin, F.Sh.; Polyakov, A.N.; Sagaidak, R.N.; Shirokovsky, I.V.; Tsyganov, Yu.S.; Voinov, Yu.S.; Gulbekian, G.G.; Bogomolov, S.L.; B. N. Gikal, A. N. Mezentsev, S. Iliev; Subbotin, V.G.; Sukhov, A.M.; Subotic, K; Zagrebaev, V.I.; Vostokin, G.K.; Itkis, M. G.; Moody, K.J; Patin, J.B.; Shaughnessy, D.A.; Stoyer, M.A.; Stoyer, N.J.; Wilk, P.A.; Kenneally, J.M.; Landrum, J.H.; Wild, J.H.; and Lougheed, R.W.
|title = Synthesis of the isotopes of elements 118 and 116 in the <sup>249</sup>Cf and <sup>245</sup>Cm+<sup>48</sup>Ca fusion reactions|journal = [[Physical Review]] C|volume = 74|issue = 4|pages = 044602|date = [[2006-10-09]]|url = http://link.aps.org/abstract/PRC/v74/e044602|doi = 10.1103/PhysRevC.74.044602|accessdate = 2007-12-08}}</ref>
[[Image:Island-of-Stability.png|thumb|250px|right|Element 118 comes right at the end of the [[island of stability]].]]

==Characteristics==
[[Image:Electron shell 118 Ununoctium.svg|thumb|200px|left|Ununoctium, like all [[noble gas]]es except [[helium]], has a "full" ([[Octet rule|eight electron]]) [[valence]] (outermost) electron shell (also called [[closed shell]]), thus making it a highly unreactive [[element]]]]

===Stability===
Although the [[half-life]] seems to be less than a [[millisecond]], it is still longer than predicted, thus giving further support to the idea of “[[island of stability]].”<ref>{{citeweb|url=http://www.dailycal.org/printable.php?id=21871|title=New Element Isolated Only Briefly |publisher=[[The Daily Californian]]|author=Andrea Lu|date=2006-10-18|accessdate=2007-12-11}}</ref> This concept, proposed by late UC Berkeley professor [[Glenn Seaborg]], explains why [[superheavy element]]s such as element 118 last longer than predicted.<ref> Glenn Considine, ed., Van Nostrand's Scientific Encyclopedia, 9th ed., (New York: Wiley Interscience, 2002, 738. ISBN 0-471-33230-5.</ref>

===Chemistry===
Ununoctium has all its electrons in a [[closed shell]] which makes it a member of the [[noble gas]] group. Therefore it is most likely that it will have similar properties as other members of the group, resembling in its chemical properties the noble gas above it in the periodic table, [[radon]].<ref>{{citeweb|url=http://www.lenntech.com/Periodic-chart-elements/Uuo-en.htm|title=Lenntech on Ununoctium - Uuo|publisher=Lenntech|accessdate=2007-12-08}}</ref> There are no known compounds of ununoctium, and because it is likely to have a high [[ionization energy]], the most common oxidation state will likely be '''0'''.<ref name="compounds">{{citeweb|publisher=WebElements Periodic Table|url =http://www.webelements.com/webelements/elements/text/Uuo/comp.html|title=Ununoctium: Binary Compounds|accessdate=2007-12-08}}</ref> It is believed to be a [[gas]] under [[normal conditions]],<ref name="apsidium"/> thus making it one of the gaseous substances with the highest molecular masses — in fact, only [[uranium hexafluoride]] (UF<sub>6</sub>) with a molecular mass of 352 would surpass it.

Since only three atoms of ununoctium have ever been produced, it currently has no uses outside of basic scientific research. Also, because it does not occur at all in the [[biosphere]] it never presents a risk, but it would constitute a [[Radiation poisoning|radiation hazard]] if enough was ever assembled in one place.<ref>{{citeweb|publisher=WebElements Periodic Table|url=http://www.webelements.com/webelements/elements/text/Uuo/biol.html|title=Ununoctium: Biological information|accessdate=2007-12-08}}</ref>


<br all>

==References==
{{reflist|2}}

==See also==
{{wikinews|Controversy-Plagued Element 118, the Heaviest Atom Yet, Finally Discovered}}
{{Commons|Ununoctium}}
*[[Discoveries of the chemical elements]]
*[[Transuranic element]]
*[[Isotopes of ununoctium]]
*[[Ununhexium]]

[[Category:Chemical elements]]
[[Category:Noble gases]]
[[Category:Synthetic elements]]

[[af:Ununoctium]]
[[als:Ununoctium]]
[[ar:أنون أوكتيوم]]
[[ast:Ununoctiu]]
[[bn:ইউনুনোকটিয়াম]]
[[be:Унуноктый]]
[[bs:Ununoktijum]]
[[ca:Ununocti]]
[[cs:Ununoctium]]
[[co:Ununoctiu]]
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[[ga:Únúnoictiam]]
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[[he:אונונאוקטיום]]
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