Wikipedia:AA-TaskForce/Ædelgasser/Ununoctium

'''Ununoctium''', også kendt som '''[[Mendelejevs forudsete grundstoffer|eka-radon]]''' eller '''grundstof 118''', er det midlertidige [[International Union of Pure and Applied Chemistry|IUPAC]] [[systematisk grundstofnavn|navn]]<ref>{{cite journal|title=Atomic weights of the elements 2005 (IUPAC Technical Report)|joural=Pure Appl. Chem.|year=2006|volume=78|issue=11|pages=2051–2066| doi=10.1351/pac200678112051| author=M.E. Wieser|journal=Pure and Applied Chemistry}}</ref> til det [[transactinide grundstof]] med [[atomnummer]]et 118 og det midlertidige symbol '''Uuo'''. I det [[periodiske system]] over grundstofferne, er stoffet et [[p-blok]]-element og det sidste i den [[7. periode]]. Ununocitum er i øjeblikket det eneste [[syntetisk grundstof|syntetiske]] medlem af [[ædelgas|gruppe 18]], og har det højeste atomnummer og den højeste [[atommasse]] tildelt et fundet grundstof. Det [[radioaktivt henfald|radioaktive]] ununoctium-atom er meget ustabilt, og siden 2002 er kun tre atomer af isotopen 294Uuo blevet opdaget.<ref>{{cite web|url=http://discovermagazine.com/2007/jan/physics/article_view?b_start:int=1&-C=|title=The Top 6 Physics Stories of 2006|accessdate=2008-01-18|date=2007-01-07|publisher=Discover Magazine}}</ref> Da dette kun tillader meget lidt eksperimentel karakterisering af stoffets egenskaber og dets [[ædelgasforbindelse|forbindelser]], har man foretaget mange teoretiske beregninger, der har givet mange forudsigelser om stoffets egenskaber, blandt andet nogle meget uventede. For eksempel kunne stoffet, der er medlem af ædelgas-gruppen, have en større kemisk reaktivitet end nogle elementer uden for denne gruppe.<ref name=Nash/> Desuden er det forudset at stoffet sandsynligvis er fast under [[standardbetingelser]].<ref name=Nash/><ref name=note/> == Historie == === Ikke-succesfulde forsøg === I slutningen af 1998 offentliggjorde den polske fysiker Robert Smolanczuk beregninger omkring fusionen af atomkerner mod syntesen af [[supertungt atom|supertunge atom]], deriblandt grundstof 118.<ref name=Smolanczuk>{{cite journal|author=Robert Smolanczuk|journal=[[Physical Review]] C|volume=59|issue=5|year=1999|month=5|title=Production mechanism of superheavy nuclei in cold fusion reactions|pages=2634–2639|doi=10.1103/PhysRevC.59.2634}}</ref> Hans beregninger viste, at det måske ville ære muligt at fremstille ununoctium ved fusion mellem [[bly]] og [[krypton]] under særdeles kontrollerede forhold.<ref name=Smolanczuk/> I 1999 brugte forskere på [[Lawrence Berkeley National Laboratory]] disse forudsigelser og offentliggjorde opdagelsen af grundstofferne [[ununhexium|116]] og 118 i en afhandling offentliggjort i ''[[Physical Review Letters]]'',<ref>{{cite journal|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 86Krypton with {{SimpleNuclide|Link|Lead|208}}|journal = [[Physical Review Letters]]|volume = 83|issue = 6–9|pages = 1104–1107|date = 1999-05-27|doi = 10.1103/PhysRevLett.83.1104}}</ref> og snart derefter rapporteredes der om resultaterne i ''[[Science]]''.<ref>{{cite journal|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}}</ref> Forskerne påstod at havde udført den kemiske reaktion: :86Krypton + 208Bly → 293Ununoctium + neutron Året efter trak de dog resultaterne tilbage, da andre forskere ikke kunne genskabe resultaterne.<ref>{{cite news|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=2008-01-18}}</ref> I juni 2002 offentliggjorde direktøren for det laboratorium, der først havde opdaget grundstoffet, at opdagelsen var baseret på data fabrikeret af hovedforfatteren [[Victor Ninov]].<ref>{{cite journal|first=Dalton|last=Rex|pages=728–729|title=Misconduct: The stars who fell to Earth|journal=[[Nature (journal)|''Nature'']]|volume=420|doi=10.1038/420728a|year=2002}}</ref> === Discovery === [[9. oktober]] [[2006]] offentliggjorde forskere fra [[Joint Institute for Nuclear Research]] (JINR) og [[Lawrence Livermore National Laboratory]] i Californien, USA, der arbejdede på JINR i [[Dubna]], [[Rusland]] i ''[[Physical Review]] C''<ref name="full"/>, at de indirekte havde sporet tre atomkerner af stoffet ununoctium-294 (en i 2002<ref>{{cite web|url=http://159.93.28.88/linkc/118/anno.html|title=Element 118: results from the first Californium249 + Calcium48 experiment|author=Oganessian Yu.Ts. et al.|publisher=Communication of the Joint Institute for Nuclear Research|year=2002|publisher+JINR Publishing Department|accessdate=2008-01-18}}</ref> og to mere i 2005) skab via kollisioner mellem [[californium]]-249-atomer og [[calcium-48]]-ioner:<ref>{{cite news|title=Livermore scientists team with Russia to discover element 118|url=https://publicaffairs.llnl.gov/news/news_releases/2006/NR-06-10-03.html|publisher=Livermore press release|date=2006-12-03|accessdate=2008-01-18}}</ref><ref>{{cite journal|author=Yu. Ts. Oganessian|title=Synthesis and decay properties of superheavy elements|journal=Pure Appl. Chem.|volume=78|pages=889–904|doi=10.1351/pac200678050889|year=2002}}</ref><ref>{{cite news|title=Heaviest element made - again|work=Nature News|publisher=[[Nature (journal)]]|date=2006-10-17|url=http://www.nature.com/news/2006/061016/full/061016-4.html|accessdate=2008-01-18}}</ref><ref>{{cite web|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=2008-01-18}}</ref><ref>{{cite web|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=2008-01-18}}</ref> : Californium249 + Calcium48 → Ununoctium294 + 3 neutroner [[Fil:Ununoctium-294 nuclear.png‎|thumb|left|200px|Vejen for det [[radioaktivt henfald|radioaktive hanfald]] fra [[isotop]]n Uuo-294.<ref name="full"/> [[Henfaldsenergi]]en og de gennemsnitlige [[halveringstid]]er er givet for '''the [[parent isotope]]''' og hvert [[henfaldsprodukt]]. Fraktionen af atomer, der undergår [[spontan fission]] (SF) er givet i grøn.]] Because of the very small [[fusion reaction]] probability (the fusion [[nuclear cross section|cross section]] is 0.5 [[Barn (unit)|pb]] = 5×10−41 m²) the experiment took 4 months and involved a beam dose of 4×1019 [[calcium]] ions that had to be shot at the [[californium]] target to produce the first recorded event believed to be the synthesis of ununoctium.<ref name="webelements">{{cite web|url=http://webelements.com/webelements/elements/text/Uuo/key.html|title=Ununoctium|publisher=WebElements Periodic Table|accessdate=2008-01-18}}</ref> Nevertheless, researchers are highly confident that the results are not a [[false positive]], since the chance that the detections were random events was estimated to be less than one part in 100,000.<ref>{{cite web|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=2008-01-18}}</ref> In the experiments, the decay of three atoms of ununoctium was observed. A [[half-life]] of 0.89 ms was calculated: {{SimpleNuclide|Ununoctium|294}} decays into {{SimpleNuclide|Link|Ununhexium|290}} by [[alpha decay]]. Since there were only three nuclei, the halflife derived from observed lifetimes has a large uncertainty: 0.89{{±|1.07|0.31}} ms.<ref name="full"/> : {{Nuclide|Ununoctium|294}} → {{Nuclide|Ununhexium|290}} + {{SimpleNuclide|Link|Helium}} The identification of the {{SimpleNuclide|Ununoctium|294}} nuclei was verified by separately creating the putative [[decay product|daughter nucleus]] {{SimpleNuclide|Ununhexium|290}} by means of a bombardment of {{SimpleNuclide|Link|Curium|245}} with {{SimpleNuclide|Link|Calcium|48}} ions, : {{Nuclide|Curium|245}} + {{Nuclide|Calcium|48}} → {{Nuclide|Ununhexium|290}} + 3 {{SubatomicParticle|link=yes|Neutron}} and checking that the {{SimpleNuclide|Ununhexium|290}} decay matched the [[decay chain]] of the {{SimpleNuclide|Ununoctium|294}} nuclei.<ref name="full"/> The daughter nucleus {{SimpleNuclide|Ununhexium|290}} is very unstable, decaying with a halflife of 14 milliseconds into {{SimpleNuclide|Link|Ununquadium|286}}, which may undergo [[spontaneous fission]] or alpha decay into {{SimpleNuclide|Link|Ununbium|282}}, which will undergo spontaneous fission.<ref name="full">{{cite journal|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 {{SimpleNuclide|Californium|249}} and {{SimpleNuclide|Curium|245}} + {{SimpleNuclide|Calcium|48}} fusion reactions|journal=[[Physical Review]] C|volume=74|issue=4|pages=044602|date=2006-10-09|doi=10.1103/PhysRevC.74.044602}}</ref> In a quantum tunneling model, the alpha decay half-life of 294118 was predicted to be 0.66(+0.23,-0.18)ms<ref name=half-lifes>{{cite journal|journal=Phys. Rev. C|volume=73|pages=014612|year=2006|title=α decay half-lives of new superheavy elements|author=P. Roy Chowdhury, C. Samanta, and D. N. Basu|month=January|day=26|doi=10.1103/PhysRevC.73.014612}}</ref> with the experimental Q-value published in 2004.<ref name=oga04>{{cite journal|journal=Phys. Rev. C|volume=70|pages=064609|year=2004|title=Measurements of cross sections and decay properties of the isotopes of elements 112, 114, and 116 produced in the fusion reactions 233, 238U, 242Pu, and 248Cm+48Ca |author=Yu. Ts. Oganessian et al.|doi=10.1103/PhysRevC.70.064609}}</ref> Calculation with theoretical Q-values from the macroscopic-microscopic model of Muntian-Hofman-Patyk-Sobiczewski gives somewhat low but comparable results.<ref name=npa07>{{ cite journal| journal=Nucl. Phys. A|volume=789|pages=142–154|year=2007| title=Predictions of alpha decay half lives of heavy and superheavy elements|author=C. Samanta, P. Roy Chowdhury and D.N. Basu|doi=10.1016/j.nuclphysa.2007.04.001}}</ref> Following the success in obtaining ununoctium, the discoverers have started similar experiments in the hope of creating [[element 120]] from {{SimpleNuclide|Link|Iron|58}} and {{SimpleNuclide|Link|Plutonium|244}}.<ref>{{cite news|url=https://www.llnl.gov/str/April07/pdfs/04_07.4.pdf|title=A New Block on the Periodic Table|date=April 2007|publisher=Lawrence Livermore National Laboratory|accessdate=2008-01-18|format=PDF}}</ref> Isotopes of the element 120 are predicted to have alpha decay half lives of the order of micro-seconds.<ref name=prc08ADNDT08>{{cite journal|journal=Phys. Rev. C|volume=77|pages=044603|year=2008|title=Search for long lived heaviest nuclei beyond the valley of stability|author=P. Roy Chowdhury, C. Samanta, and D. N. Basu|doi=10.1103/PhysRevC.77.044603}}</ref><ref name="sciencedirect1">{{cite journal|journal=At. Data & Nucl. Data Tables|year=2008|title=Nuclear half-lives for α -radioactivity of elements with 100 ≤ Z ≤ 130|author=P. Roy Chowdhury, C. Samanta, and D. N. Basu|url=http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6WBB-4S26JRX-1&_user=2806701&_coverDate=03%2F14%2F2008&_alid=740505626&_rdoc=6&_fmt=high&_orig=search&_cdi=6706&_sort=d&_docanchor=&view=c&_ct=211&_acct=C000058844&_version=1&_urlVersion=0&_userid=2806701&md5=dc85a3a8a2ac1faa38c3804f16f86c13}}</ref> {{clear}} == Naming == ''Element 118'' is still called ''[[Mendeleev's predicted elements|eka-radon]]''{{kilde mangler|dato=(sandkasse eller diskussionsside)}}, but until the 1960s it was also known as ''eka-emanation'' (for the old name for radon).<ref name=60s/> Only in 1979 the [[IUPAC]] published recommendations according to which the element started to be called ''ununoctium''.<ref>{{cite journal|author=J. Chatt|journal=Pure Appl. Chem.|year=1979|volume=51|pages=381–384|title=Recommendations for the Naming of Elements of Atomic Numbers Greater than 100|doi=10.1351/pac197951020381}}</ref> The name ''ununoctium'' is a [[systematic element name]], used as a [[placeholder name|placeholder]] until it is confirmed by other research groups and the IUPAC decides on a name. Before the retraction in 2002, the researchers from Berkeley had intended to name the element ''ghiorsium (Gh)'', after [[Albert Ghiorso]] (a leading member of the research team).<ref>{{cite web|title=Discovery of New Elements Makes Front Page News|url=http://lbl.gov/Science-Articles/Research-Review/Magazine/1999/departments/breaking_news.shtml|publisher=Berkeley Lab Research Review Summer 1999|year=1999|accessdate=2008-01-18}}</ref> Several years later, when the Russian discoverers reported their synthesis in 2006, rumors appeared that they were planning on calling it after the place of the discovery, ''dubnadium (Dn)'' (very similar to the name of [[dubnium|the 105th element, dubnium (Db)]]).<ref>{{cite web|title= Origins of the Element Names-Names Constructed from other Words|author=D. Trapp|url=http://homepage.mac.com/dtrapp/Elements/combination2.html#116 |accessdate=2008-01-18}}</ref> Nevertheless, during an interview with a Russian newspaper, the head of the Russian institute stated the team were considering two names for the new element, ''Flyorium'' in honor of [[Georgy Flyorov]], the founder of the research institute; and ''moskovium'' (also spelled ''moscovium'' or even ''moscowium''), in recognition of the [[Moscow Oblast]] where Dubna lies.<ref>{{cite web|url=http://news.rin.ru/eng/news/9886/9/6/|title=New chemical elements discovered in Russia`s Science City|date=2007-02-12|accessdate=2008-02-09}}</ref> He also stated that although the element was discovered as an American collaboration, who provided the californium target, the element should rightly be named in honour of Russia since the Flerov Laboratory of Nuclear Reactions at JINR is the only facility in the world which can achieve this result.<ref>{{cite web|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=2008-01-18|lang=ru}}</ref><ref>{{cite web|last=Yemel'yanova|language=Russian|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=2008-01-18|lang=ru}}</ref> == Characteristics == === Nucleus stability and isotopes === [[Fil:Island-of-Stability.png|thumb|250px|right|Element 118 comes right at the end of the "island of stability" and thus its nuclei are slightly more stable than predicted.]] {{seealso|Island of stability|Isotopes of ununoctium}} There are no elements with an [[atomic number]] above 82 (after [[lead]]) that have stable isotopes. The stability of nuclei decreases with the increase in atomic number, such that all isotopes with an atomic number above [[mendelevium|101]] [[radioactive decay|decay radioactively]] with a [[halflife]] under a day. Nevertheless, due to [[magic number (physics)|reasons]] not very well understood yet, there is a slight increased nuclear stability around elements 110–114, which leads to the appearance of what is known in nuclear physics as the "[[island of stability]]". This concept, proposed by [[UC Berkeley]] professor [[Glenn Seaborg]], explains why [[superheavy element]]s last longer than predicted.<ref>{{cite book|title=Van Nostrand's scientific encyclopedia|author=Glenn D Considine; Peter H Kulik|publisher=Wiley-Interscience|year=2002|edition=9|isbn=9780471332305}}</ref> Ununoctium is [[radioactive]] and has [[half-life]] that appears to be less than a [[millisecond]]. Nonetheless, this is still longer than some predicted values,<ref name=half-lifes>{{cite journal|journal=Phys. Rev. C|volume=73|pages=014612|year=2006|title=α decay half-lives of new superheavy elements|author=P. Roy Chowdhury, C. Samanta, and D. N. Basu|month=January|day=26|doi=10.1103/PhysRevC.73.014612}}</ref><ref>{{cite journal|title=Heaviest nuclei from 48Ca-induced reactions|author=Yuri Oganessian|year=2007|journal=J. Phys. G: Nucl. Part. Phys.|volume=34|pages=R165–R242|doi=10.1088/0954-3899/34/4/R01}}</ref> thus giving further support to the idea of this "island of stability"..<ref>{{cite web|url=http://www.dailycal.org/printable.php?id=21871|title=New Element Isolated Only Briefly|publisher=[[The Daily Californian]]|date=2006-10-18|accessdate=2008-01-18}}</ref> Quantum tunneling model predicts existence of several neutron-rich isotopes of the element 118 with alpha decay half lives close to ms.<ref name=prc08ADNDT08>{{cite journal|journal=Phys. Rev. C|volume=77|pages=044603|year=2008|title=Search for long lived heaviest nuclei beyond the valley of stability|author=P. Roy Chowdhury, C. Samanta, and D. N. Basu|doi=10.1103/PhysRevC.77.044603}}</ref><ref name="sciencedirect1"/> Theoretical calculations done on the synthetic pathways for, and the halflife of, other [[isotopes of ununoctium|isotopes]] have shown that some could be slightly more [[stable isotope|stable]] than the synthesized isotope {{SimpleNuclide|Ununoctium|294}}, most likely {{SimpleNuclide|Ununoctium|293}}, {{SimpleNuclide|Ununoctium|295}}, {{SimpleNuclide|Ununoctium|296}}, {{SimpleNuclide|Ununoctium|297}}, {{SimpleNuclide|Ununoctium|298}}, {{SimpleNuclide|Ununoctium|300}} and {{SimpleNuclide|Ununoctium|302}}.<ref name=half-lifes/><ref name=odd>{{cite journal|journal=Nuclear Physics A|volume=730|year=2004|pages=355–376|title=Entrance channels and alpha decay half-lives of the heaviest elements|author=G. Royer, K. Zbiri, C. Bonilla|doi=10.1016/j.nuclphysa.2003.11.010}}</ref> Of these, {{SimpleNuclide|Ununoctium|297}} might provide the best chances for obtaining longer-lived nuclei,<ref name=half-lifes/><ref name=odd/> and thus might become the focus of future work with this element. Some isotopes with many more neutrons, such as some located around {{SimpleNuclide|Ununoctium|313}}, could also provide longer-lived nuclei.<ref>{{cite journal|title=Half-life predictions for decay modes of superheavy nuclei|year=2004|journal=J. Phys. G: Nucl. Part. Phys.|volume=30|pages=1487–1494|doi=10.1088/0954-3899/30/10/014|author=S B Duarte, O A P Tavares, M Gonçalves, O Rodríguez, F Guzmán, T N Barbosa, F García and A Dimarco}}</ref> === Properties === {{seealso|Noble gas}} Ununoctium is a member of the [[inert]] gases, the zero-[[valency (chemistry)|valence]] elements. Consequently, ununoctium is expected to have similar physical and chemical properties to other members of its group, most closely resembling the noble gas above it in the periodic table, [[radon]].<ref>{{cite web|url=http://lenntech.com/Periodic-chart-elements/Uuo-en.htm|title=Ununoctium (Uuo) - Chemical properties, Health and Environmental effects|publisher=Lenntech|accessdate=2008-01-18}}</ref> The members of this group are inert to most common chemical reactions (such as combustion, for example) because the outer [[valence shell]] is completely filled with [[octet rule|eight electrons]]. This produces a stable, minimum energy configuration in which the outer electrons are tightly bound.<ref>{{cite web|last=Bader|first=Richard F.W.|url=http://miranda.chemistry.mcmaster.ca/esam/|title=An Introduction to the Electronic Structure of Atoms and Molecules|publisher=McMaster University|accessdate=2008-01-18}}</ref> It is thought that similarly, ununoctium has a [[closed shell|closed]] outer valence shell in which its [[valence electron]]s are arranged in a 7s², 7p6 [[electron configuration|configuration]].<ref name=Nash/> [[Fil:Electron shell 118 Ununoctium.svg|thumb|200px|left|The expected [[electron shell]] diagram for ununoctium. Note the [[octet rule|eight electrons]] in the [[valence shell|outer shell]].]] Following the [[periodic trend]], ununoctium is expected to be slightly more reactive than radon; but theoretical calculations have shown that it could be quite reactive for its "noble" labeling.<ref name=Kaldor>{{cite book|title=Theoretical Chemistry and Physics of Heavy and Superheavy Elements|author=Uzi Kaldor, Stephen Wilson|pages=105|year=2003|publisher=Springer|isbn=140201371X}}</ref> In addition to being far more reactive than radon, ununoctium may be even more reactive than elements [[element 114|114]] and [[element 112|112]].<ref name=Nash>{{cite journal|title=Atomic and Molecular Properties of Elements 112, 114, and 118|author=Clinton S. Nash|journal=J. Phys. Chem. A|year=2005|volume=109|issue=15|pages=3493–3500|doi=10.1021/jp050736o}}</ref> The reason for the apparent enhancement of the chemical activity of element 118 relative to radon is an energetic destabilization and a radial expansion of the last occupied 7p [[subshell]].<ref name=Nash/><ref>the actual quote is: ''"The reason for the apparent enhancement of chemical activity of element 118 relative to radon is the energetic destabilization and radial expansion of its occupied 7p3/2 [[spinor]] shell"''</ref> More precisely, considerable [[spin-orbit interaction]]s between the 7p electrons with the inert 7s² electrons, effectively lead to a second valence shell closing at [[element 114]], and a significant decrease in stabilization of the closed shell of element 118.<ref name=Nash/> It has also been calculated that ununoctium, unlike other noble gases, binds an electron with release of energy—or in other words, it exhibits positive [[electron affinity]].<ref name=Pyykko>{{cite journal|title=QED corrections to the binding energy of the eka-radon (Z=118) negative ion|author=Igor Goidenko, Leonti Labzowsky, Ephraim Eliav, Uzi Kaldor, and Pekka Pyykko¨|journal=Physical Review A|volume=67|year=2003|pages=020102(R)|doi=10.1103/PhysRevA.67.020102}}</ref><ref>{{cite journal|volume=77|issue=27|journal=Physical Review Letters|date=1996-12-30|title=Element 118: The First Rare Gas with an Electron Affinity|author=Ephraim Eliav and Uzi Kaldor|url=http://prola.aps.org/abstract/PRL/v77/i27/p5350_1|accessdate=2008-01-18}}</ref><ref>Nevertheless, [[quantum electrodynamic]] corrections have been shown to be quite significant in reducing this affinity (by decreasing the binding in the [[anion]] Uuo− by 9%) thus confirming the importance of these corrections in [[superheavy atom]]s. ''See Pyykko''</ref> Ununoctium is expected to have by far the broadest [[polarizability]] of all elements before it in the periodic table, and almost twofold of radon.<ref name=Nash/> By extrapolating this to the other noble gases, it is expected that ununoctium has a boiling point between 320 and 380 K.<ref name=Nash/> This is very different from the previously estimated values of 263 K<ref name=Seaborg>{{cite book|title=Modern Alchemy|author=Glenn Theodore Seaborg|year=1994|page=172|isbn=9810214405|publisher=World Scientific}}</ref> or 247 K.<ref>{{cite journal|journal=Journal of Radioanalytical and Nuclear Chemistry|volume=251|issue=2|year=2002|pages=299–301|title=Boiling points of the superheavy elements 117 and 118|author=N. Takahashi|doi=10.1023/A:1014880730282}}</ref> Even given the large uncertainties of the calculations, it seems highly unlikely that element 118 would be a gas under [[standard conditions]].<ref name=Nash/><ref name=note>It is debatable if the name of the group 'noble gases' will be changed if ununoctium is shown to be non-volatile.</ref> And as the liquid range of the other gases is very narrow, between 2 and 9 kelvins, this element should be [[solid]] at standard conditions. If ununoctium forms a [[gas]] under standard conditions nevertheless, it would be one of the densest substances gaseous at standard conditions (even if it is [[monatomic]] like the other noble gases). Because of its tremendous polarizability, ununoctium is expected to have an anomalously low [[ionization potential]] (similar to that of [[lead]] which is 70% of that of radon<ref name=hydride>{{cite journal|journal=Journal of Chemical Physics|volume=112|issue=6|date=2000-02-08|title=Spin–orbit effects on the transactinide p-block element monohydrides MH (M=element 113–118)|author=Young-Kyu Han, Cheolbeom Bae, Sang-Kil Son, and Yoon Sup Lee|url=http://link.aip.org/getpdf/servlet/GetPDFServlet?filetype=pdf&id=JCPSA6000112000006002684000001|accessdate=2008-01-18}}</ref> and significantly smaller than that of element 114<ref>{{cite journal|journal=J. Phys. Chem. A|volume=1999|issue=3|pages=402–410|title=Spin-Orbit Effects, VSEPR Theory, and the Electronic Structures of Heavy and Superheavy Group IVA Hydrides and Group VIIIA Tetrafluorides. A Partial Role Reversal for Elements 114 and 118|author=Clinton S. Nash|doi=10.1021/jp982735k|year=1999}}</ref>) and a standard state [[condensed phase]].<ref name=Nash/> === Compounds and uses === [[Fil:Square-planar-3D-balls.png|right|130px|thumb|{{chem|Xe||F|4}} and {{chem|Rn||F|4}} have a square planar configuration]] [[Fil:Tetrahedral-3D-balls.png|right|130px|thumb|{{chem|Uuo||F|4}} is predicted to have a tetrahedral configuration]] {{seealso|Noble gas compound}} No compounds of ununoctium have been synthesized yet, but calculations on [[theoretical chemistry|theoretical compounds]] have been performed since 1964.<ref name=60s>{{cite journal|doi=10.1016/0022-1902(65)80255-X|year=1965|publisher=Elsevier Science Ltd.|title=Some physical and chemical properties of element 118 (Eka-Em) and element 86 (Em)|author=A. V. Grosse|journal=Journal of Inorganic and Nuclear Chemistry|volume=27|issue=3|pages=509–19}}</ref> It is expected that if the [[ionization energy]] of the element is high enough, it will be difficult to [[oxidize]] and therefore, the most common [[oxidation state]] will be 0 (as for other noble gases).<ref name="compounds">{{cite web|publisher=WebElements Periodic Table|url=http://webelements.com/webelements/elements/text/Uuo/comp.html|title=Ununoctium: Binary Compounds|accessdate=2008-01-18}}</ref> Calculations on the [[dimer]]ic [[molecule]] {{chem|Uuo|2}} showed a [[chemical bond|bonding]] interaction roughly equivalent to that calculated for [[dimercury|{{chem|Hg|2}}]], and a [[dissociation energy]] of 6 kJ/mol, roughly 4 times of that of {{chem|Rn|2}}.<ref name=Nash/> But most strikingly, it was calculated to have a [[bond length]] shorter than in {{chem|Rn|2}} by .16 Å, which would be indicative of a significant bonding interaction.<ref name=Nash/> On the other hand, the compound UuoH+ exhibits a dissociation energy (in other words [[proton affinity]] of Uuo) that is smaller than that of RnH+.<ref name=Nash/> The bonding between ununoctium and [[hydrogen]] in UuoH is very weak and can be regarded as a pure [[van der Waals interaction]] rather than a true [[chemical bond]].<ref name=hydride/> On the other hand, with highly electronegative elements, ununoctium seems to form more stable compounds than for example [[element 112]] or [[element 114]].<ref name=hydride/> The stable oxidation states +2 and +4 have been predicted to exist in the [[fluor]]inated compounds {{chem|Uuo||F|2}} and {{chem|Uuo||F|4}}.<ref name=fluoride>{{cite journal|journal=J. Phys. Chem. A|volume=103|issue=8|pages=1104–1108|date=1999-02-09|title=Structures of RgFn (Rg = Xe, Rn, and Element 118. n = 2, 4.) Calculated by Two-component Spin-Orbit Methods. A Spin-Orbit Induced Isomer of (118)F4|author=Young-Kyu Han and Yoon Sup Lee|doi=10.1021/jp983665k}}</ref> This is a result of the same spin-orbit interactions that make ununoctium unusually reactive. For example, it was shown that the reaction of Uuo with {{chem|F|2}} to form the compound {{chem|Uuo||F|2}}, would release an energy of 106 kcal/mol of which about 46 kcal/mol come from these interactions.<ref name=hydride/> For comparison, the spin-orbit interaction for the similar molecule {{chem|Rn||F|2}} is about 10 kcal/mol out of a formation energy of 49 kcal/mol.<ref name=hydride/> The same interaction stabilizes the [[tetrahedral molecular geometry|tetrahedral Td configuration]] for {{chem|Uuo||F|4}}, as opposed to the [[square planar|square planar D4h one]] of [[xenon tetrafluoride|{{chem|Xe||F|4}}]] and {{chem|Rn||F|4}}.<ref name=fluoride/> The Uuo-F bond will most probably be [[ionic bond|ionic]] rather than [[covalent bond|covalent]], rendering the {{chem|Uuo||F|n}} compounds non-volatile.<ref name=Kaldor/><ref>{{cite journal|journal=J. Chem. Soc., Chem. Commun.|year=1975|pages=760b–761|doi=10.1039/C3975000760b|title=Fluorides of radon and element 118|author=Kenneth S. Pitzer}}</ref> Unlike the other noble gases, ununoctium was predicted to be sufficiently [[electropositive]] to form a Uuo-Cl bond with [[chlorine]].<ref name=Kaldor/> Since only three atoms of ununoctium have ever been produced, it currently has no uses outside of basic scientific research. It would constitute a [[radiation poisoning|radiation hazard]] if enough were ever assembled in one place.<ref name=70s>{{cite web|publisher=WebElements Periodic Table|url=http://webelements.com/webelements/elements/text/Uuo/biol.html|title=Ununoctium: Biological information|accessdate=2008-01-18}}</ref> == References == {{reflist|2}} == See also == {{wikinews|Controversy-Plagued Element 118, the Heaviest Atom Yet, Finally Discovered}} {{Commons|Ununoctium}} * [[Transuranic element]] * [[Ununhexium]] == External links == * [http://web.archive.org/web/20061129112314/http://flerovlab.jinr.ru/flnr/elm118.html ELEMENT 118: EXPERIMENTS on DISCOVERY], archive of discoverers' official web page * [http://www.chemistry-blog.com/2006/10/16/discovery-of-element-118-by-oganessian-dont-call-it-ununoctium/ Chemistry-Blog: Independent analysis of 118 claim] * [http://webelements.com/ununoctium/ WebElements: Ununoctium] * [http://www.apsidium.com/elements/118.htm Apsidium: Ununoctium - Moskowium] * [http://education.jlab.org/itselemental/ele118.html It's Elemental: Ununoctium] * [http://iupac.org/publications/pac/75/10/1601/ On the Claims for Discovery of Elements 110, 111, 112, 114, 116, and 118 (IUPAC Technical Report)]