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'{{Временная статья|Унуноктий}} {{Карточка химического элемента | имя = Унуно́ктий / Ununoctium (Uuo) | символ = Uuo | номер = 118 | внешний вид = | атомная масса = 294 | радиус атома = 152 | энергия ионизации 1 = 975±155 кДж·моль⁻¹ | конфигурация = [Rn]&nbsp;5f¹⁴&nbsp;6d¹⁰&nbsp;7s^{<nowiki>2</nowiki>}&nbsp;7p⁶ | ковалентный радиус = 230 | радиус иона = | электроотрицательность = | электродный потенциал = | степени окисления = -1, 0, +1, +2, +4, +6, +8 | плотность = (предположительно) 13.65 г·см^-3 | теплоёмкость = | теплопроводность = | температура плавления = | теплота плавления = 23.5 кДж·моль⁻¹ | температура кипения = 350±30 K, 80±30 °C, 170±50 °F | теплота испарения = 19.4 кДж·моль⁻¹ | молярный объём = | структура решётки = | параметры решётки = | отношение c/a = | температура Дебая = }}{{Элемент периодической системы|align=center|fontsize=100%|number=118}} '''Унуноктий''' —is the temporary [[International Union of Pure and Applied Chemistry|IUPAC]] [[systematic element name|name]]<ref>{{cite journal|title=Atomic weights of the elements 2005 (IUPAC Technical Report)|journal=Pure Appl. Chem.|year=2006|volume=78|issue=11|pages=2051–2066| doi=10.1351/pac200678112051| author=Wieser, M.E.}}</ref> for the [[transactinide element]] with the [[atomic number]] 118 and temporary [[chemical symbol|element symbol]] '''Uuo'''. It is also known as '''[[Mendeleev's predicted elements|eka-radon]]''' or '''element 118''', and on the [[periodic table (standard)|periodic table]] of the elements it is a [[p-block]] element and the last one of the [[period 7|7th period]]. Ununoctium is currently the only [[synthetic element|synthetic]] member of [[Group 18 element|group&nbsp;18]]. It has the highest atomic number and highest [[atomic mass]] of all the elements discovered so far. The [[radioactive decay|radioactive]] ununoctium atom is very unstable, due to its high mass, and since 2005, only three or possibly four atoms of the [[isotopes of ununoctium|isotope ²⁹⁴Uuo]] have been detected.<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> Although this allowed very little experimental characterization of its properties and possible [[Chemical compound|compounds]], theoretical calculations have resulted in many predictions, including some unexpected ones. For example, although ununoctium is a member of group&nbsp;18, it may possibly not be a [[noble gas]], unlike all the other group&nbsp;18 elements.<ref name=Nash/> It was formerly thought to be a gas under [[standard conditions for temperature and pressure|normal conditions]] but is now predicted to be a [[solid]] due to [[Relativistic quantum chemistry|relativistic effects]].<ref name=Nash/> ==History== {{see also|Discoveries of the chemical elements}} ===Unsuccessful synthesis attempts=== In late 1998, Polish physicist [[Robert Smolańczuk]] published calculations on the fusion of atomic nuclei towards the synthesis of [[superheavy element|superheavy atoms]], including ununoctium.<ref name=Smolanczuk>{{cite journal|author=Smolanczuk, R.|journal=[[Physical Review]] C|volume=59|issue=5|year=1999|title=Production mechanism of superheavy nuclei in cold fusion reactions|pages=2634–2639|doi=10.1103/PhysRevC.59.2634|bibcode = 1999PhRvC..59.2634S}}</ref> His calculations suggested that it might be possible to make ununoctium by fusing [[lead]] with [[krypton]] under carefully controlled conditions.<ref name=Smolanczuk/> In 1999, researchers at [[Lawrence Berkeley National Laboratory]] made use of these predictions and announced the discovery of [[livermorium]] and ununoctium, in a paper published in ''[[Physical Review Letters]]'',<ref>{{cite journal|last=Ninov|first=Viktor|displayauthors=1|title=Observation of Superheavy Nuclei Produced in the Reaction of {{SimpleNuclide|Link|Krypton|86}} with {{SimpleNuclide|Link|Lead|208}}|journal=[[Physical Review Letters]]|volume=83|pages=1104–1107|year=1999|doi=10.1103/PhysRevLett.83.1104|bibcode=1999PhRvL..83.1104N|issue=6}}</ref> and very soon after the results were reported in ''[[Science (journal)|Science]]''.<ref>{{cite journal|author=Service, R. F.|journal=Science|year=1999|volume=284|page=1751|doi=10.1126/science.284.5421.1751|title=Berkeley Crew Bags Element 118|issue=5421}}</ref> The researchers reported to have performed the [[nuclear reaction|reaction]] :{{Nuclide|Krypton|86}} + {{Nuclide|Lead|208}} → {{Nuclide|Ununoctium|293}} + {{SubatomicParticle|link=yes|Neutron}}. The following year, they published a retraction after researchers at other laboratories were unable to duplicate the results and the Berkeley lab itself was unable to duplicate them as well.<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> 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>{{cite journal|pages=728–729|title=Misconduct: The stars who fell to Earth|journal=[[Nature (journal)|Nature]]|volume=420|doi=10.1038/420728a|year=2002|pmid=12490902|last1=Dalton|first1=R.|issue=6917|bibcode = 2002Natur.420..728D }}</ref><ref>[http://physicsworld.com/cws/article/news/2629 Element 118 disappears two years after it was discovered]. Physicsworld.com. Retrieved on 2012-04-02.</ref> ===Discovery reports=== The first decay of atoms of ununoctium was observed at the [[Joint Institute for Nuclear Research]] (JINR) by [[Yuri Oganessian]] and his group in [[Dubna]], Russia, in 2002.<ref name="pp2002">{{cite journal|author=Oganessian, Yu. T. et al.|title=Results from the first {{chem|249|Cf}}+{{chem|48|Ca}} experiment|url=http://www.jinr.ru/publish/Preprints/2002/287(D7-2002-287)e.pdf|journal=JINR Communication|location=JINR, Dubna|year=2002}}</ref> On October 9, 2006, researchers from JINR and [[Lawrence Livermore National Laboratory]] of California, US, working at the JINR in Dubna, announced<ref name="synthesis-118-116"/> that they had indirectly detected a total of three (possibly four) nuclei of ununoctium-294 (one or two in 2002<ref>{{cite web|url=http://web.archive.org/web/20110722060249/http://159.93.28.88/linkc/118/anno.html|title=Element 118: results from the first {{SimpleNuclide|Californium|249}} + {{SimpleNuclide|Calcium|48}} experiment|author=Oganessian, Yu. T. ''et al.''|publisher=Communication of the Joint Institute for Nuclear Research|year=2002}}</ref> and two more in 2005) produced via collisions of [[californium]]-249 atoms and [[calcium-48]] ions.<ref>{{cite news|title=Livermore scientists team with Russia to discover element 118|url=https://www.llnl.gov/news/newsreleases/2006/NR-06-10-03.html|publisher=Livermore press release|date=2006-12-03|accessdate=2008-01-18}}</ref><ref>{{cite journal|author=Oganessian, Yu. T.|title=Synthesis and decay properties of superheavy elements|journal=Pure Appl. Chem.|volume=78|pages=889–904|doi=10.1351/pac200678050889|year=2006|issue=5}}</ref><ref>{{cite journal|title=Heaviest element made – again|journal=Nature News|publisher=[[Nature (journal)|Nature]]|year=2006|doi=10.1038/news061016-4|author= Sanderson, K.}}</ref><ref>{{cite web|author=Schewe, P. and Stein, B.|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=Weiss, R.|date=2006-10-17|accessdate=2008-01-18}}</ref> :{{Nuclide|Link|Californium|249}} + {{Nuclide|Link|Calcium|48}} → {{Nuclide|Link|Ununoctium|294}} + 3 {{SubatomicParticle|link=yes|Neutron}}. [[File:Ununoctium-294 nuclear.svg|thumb|left|200px|alt=Schematic diagram of ununoctium-294 alpha decay, with a half-life of 0.89&nbsp;ms and a decay energy of 11.65&nbsp;MeV. The resulting livermorium-290 decays by alpha decay, with a half-life of 10.0&nbsp;ms and a decay energy of 10.80&nbsp;MeV, to flerovium-286. Flerovium-286 has a half-life of 0.16&nbsp;s and a decay energy of 10.16&nbsp;MeV, and undergoes alpha decay to copernicium-282 with a 0.7 rate of spontaneous fission. Copernicium itself has a half-life of only 1.9&nbsp;ms and has a 1.0 rate of spontaneous fission.|[[Radioactive decay]] pathway of the [[isotope]] ununoctium-294.<ref name="synthesis-118-116"/> The [[decay energy]] and average [[half-life]] is given for the [[parent isotope]] and each [[daughter isotope]]. The fraction of atoms undergoing [[spontaneous fission]] (SF) is given in green.]] In 2011, [[International Union of Pure and Applied Chemistry|IUPAC]] evaluated the 2006 results of the Dubna-Livermore collaboration and concluded: "The three events reported for the Z = 118 isotope have very good internal redundancy but with no anchor to known nuclei do not satisfy the criteria for discovery".<ref>{{cite journal|doi=10.1351/PAC-REP-10-05-01|title=Discovery of the elements with atomic numbers greater than or equal to 113 (IUPAC Technical Report)|year=2011|last1=Barber|first1=Robert C.|last2=Karol|first2=Paul J.|last3=Nakahara|first3=Hiromichi|last4=Vardaci|first4=Emanuele|last5=Vogt|first5=Erich W.|journal=Pure and Applied Chemistry|page=1|volume=83|issue=7}}</ref> Because of the very small [[fusion reaction]] probability (the fusion [[nuclear cross section|cross section]] is {{gaps|~|0.3–0.6|u=[[Barn (unit)|pb]]}} or {{val|p=(|3|end=–6)|e=-41|u=m2}}) the experiment took four months and involved a beam dose of {{val|4|e=19}} [[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 {{val|100000}}.<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 alpha-decay of three atoms of ununoctium was observed. A fourth decay by direct [[spontaneous fission]] was also proposed. A [[half-life]] of 0.89&nbsp;ms was calculated: {{chem|294|Uuo}} decays into {{chem|link=Isotopes of livermorium#Livermorium-290|290|Lv}} by [[alpha decay]]. Since there were only three nuclei, the half-life derived from observed lifetimes has a large uncertainty: {{val|0.89|+1.07|-0.31|u=ms}}.<ref name="synthesis-118-116"/> :{{Nuclide|Ununoctium|294}} → {{Nuclide|livermorium|290}} + {{Nuclide|Link|helium|4}} The identification of the {{chem|294|Uuo}} nuclei was verified by separately creating the putative [[decay product|daughter nucleus]] {{chem|290|Lv}} directly by means of a bombardment of {{chem|link=curium-245|245|Cm}} with {{chem|link=calcium-48|48|Ca}} ions, :{{Nuclide|Curium|245}} + {{Nuclide|Calcium|48}} → {{Nuclide|livermorium|290}} + 3 {{SubatomicParticle|link=yes|Neutron}}, and checking that the {{chem|290|Lv}} decay matched the [[decay chain]] of the {{chem|294|Uuo}} nuclei.<ref name="synthesis-118-116"/> The daughter nucleus {{chem|290|Lv}} is very unstable, decaying with a lifetime of 14 milliseconds into {{chem|link=flerovium-286|286|Fl}}, which may experience either [[spontaneous fission]] or alpha decay into {{chem|link=copernicium-282|282|Cn}}, which will undergo spontaneous fission.<ref name="synthesis-118-116">{{cite journal|last1=Oganessian|first1=Yu. T.|first2=V. K.|last2=Utyonkov|displayauthors=1|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|year=2006|doi=10.1103/PhysRevC.74.044602|bibcode = 2006PhRvC..74d4602O}}</ref> In a quantum-tunneling model, the alpha decay half-life of {{chem|294|Uuo}} was predicted to be {{val|0.66|+0.23|-0.18|u=ms}}<ref name=half-lives/> with the experimental Q-value published in 2004.<ref name=oga04>{{cite 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=Samanta, C.; Chowdhury, R. P.; Basu, D.N.|doi=10.1016/j.nuclphysa.2007.04.001|arxiv = nucl-th/0703086 |bibcode = 2007NuPhA.789..142S}}</ref> {{clear}} ==Naming== Until the 1960s ununoctium was known as ''eka-emanation'' (emanation is the old name for [[radon]]).<ref name=60s/> In 1979 the [[IUPAC]] published recommendations according to which the element was to be called ''ununoctium'',<ref name=iupac>{{cite journal|author=Chatt, J.|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|issue=2}}</ref> a [[systematic element name]], as a [[placeholder name|placeholder]] until the discovery of the element is confirmed 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> The Russian discoverers reported their synthesis in 2006. In 2007, 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 laboratory in Dubna; and ''moskovium'', in recognition of the [[Moscow Oblast]] where Dubna is located.<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 honor of Russia since the Flerov Laboratory of Nuclear Reactions at JINR was the only facility in the world which could achieve this result.<ref>{{cite web|last=Yemel'yanova|language=Russian|first=Asya |date=2006-12-17|url=http://www.vesti.ru/doc.html?id=113947|title=118-й элемент назовут по-русски (118th element will be named in Russian)|publisher=vesti.ru|accessdate=2008-01-18}}</ref> These names were later proposed for [[flerovium|element 114]] (flerovium) and [[livermorium|element 116]] (moscovium).<ref>{{cite web|publisher=rian.ru|year=2011|accessdate=2011-05-08|url=http://ria.ru/science/20110326/358081075.html|title=Российские физики предложат назвать 116 химический элемент московием (Russian Physicians Will Suggest to Name Element 116 Moscovium)|language=Russian}}</ref> However, the final name proposed for element 116 was instead ''livermorium''.<ref name=IUPAC>{{cite web|title=News: Start of the Name Approval Process for the Elements of Atomic Number 114 and 116|url=http://www.iupac.org/news/news-detail/article/start-of-the-name-approval-process-for-the-elements-of-atomic-number-114-and-116.html|work=International Union of Pure and Applied Chemistry|accessdate=2011-12-02}}</ref> No name has yet been officially suggested for the element as no claims for discovery have yet been accepted by the IUPAC. According to current guidelines from IUPAC, the ultimate name for all new elements should end in "-ium", which means the name for ununoctium will almost certainly end in "-ium", not "-on", even if ununoctium turns out to be a [[noble gas]], which traditionally have names ending in "-on" (with the exception of [[helium]], which was not known to be a noble gas when it was discovered).<ref>{{cite journal|doi=10.1351/pac200274050787|url=http://media.iupac.org/publications/pac/2002/pdf/7405x0787.pdf|title=Naming of new elements (IUPAC Recommendations 2002)|year=2002|author=Koppenol, W. H.|journal=Pure and Applied Chemistry|volume=74|page=787|issue=5}}</ref> ==Characteristics== ===Nuclear stability and isotopes=== [[File:Island of Stability derived from Zagrebaev.png|thumb|400px|Ununoctium (row 118) is slightly above the "island of stability" (white circle) and thus its nuclei are slightly more stable than otherwise predicted.]] {{main|Isotopes of ununoctium}} {{see also|Island of stability}} The stability of nuclei decreases greatly with the increase in atomic number after [[plutonium]], the heaviest [[primordial element]], so that all isotopes with an atomic number above [[mendelevium|101]] [[radioactive decay|decay radioactively]] with a [[half-life]] under a day, with an exception of [[dubnium]]-268. No elements with [[atomic number]]s above 82 (after [[lead]]) have stable isotopes.<ref>{{cite journal |last1 =de Marcillac|first1 = Pierre |first2= Noël |last2=Coron |first3=Gérard |last3=Dambier |first4=Jacques |last4=Leblanc |first5=Jean-Pierre |last5=Moalic |date=April 2003|title = Experimental detection of α-particles from the radioactive decay of natural bismuth|journal = Nature|volume = 422|pages = 876–878|pmid=12712201|doi = 10.1038/nature01541|issue = 6934|bibcode = 2003Natur.422..876D}}</ref> Nevertheless, because of [[magic number (physics)|reasons]] not very well understood yet, there is a slightly increased nuclear stability around atomic numbers [[darmstadtium|110]]–[[flerovium|114]], which leads to the appearance of what is known in nuclear physics as the "[[island of stability]]". This concept, proposed by [[University of California, Berkeley|University of California]] professor [[Glenn Seaborg]], explains why [[superheavy element]]s last longer than predicted.<ref>{{cite book|title=Van Nostrand's scientific encyclopedia|first1=Glenn D. |last1= Considine |first2=Peter H. |last2= Kulik|publisher=Wiley-Interscience|year=2002|edition=9|isbn=978-0-471-33230-5|oclc=223349096}}</ref> Ununoctium is [[radioactive]] and has a [[half-life]] that appears to be less than a [[millisecond]]. Nonetheless, this is still longer than some predicted values,<ref name=half-lives/><ref>{{cite journal|title=Heaviest nuclei from 48Ca-induced reactions|first=Yu. T.|last=Oganessian|year=2007|journal= Journal of Physics G: Nuclear and Particle Physics|volume=34|pages=R165–R242|doi=10.1088/0954-3899/34/4/R01|bibcode = 2007JPhG...34..165O|issue=4}}</ref> thus giving further support to the idea of this "island of stability".<ref>{{cite web|url=http://archive.dailycal.org/article.php?id=21871|title=New Element Isolated Only Briefly|publisher=[[The Daily Californian]]|date=2006-10-18|accessdate=2008-01-18}}</ref> Calculations using a quantum-tunneling model predict the existence of several neutron-rich isotopes of ununoctium with alpha-decay half-lives close to 1&nbsp;ms.<ref name=prc08ADNDT08>{{cite journal|journal=Physical Reviews C|volume=77|page=044603|year=2008|title=Search for long lived heaviest nuclei beyond the valley of stability|first1=Roy P.|last1=Chowdhury |first2=C. |last2=Samanta |first3= D. N. |last3=Basu|doi=10.1103/PhysRevC.77.044603|bibcode = 2008PhRvC..77d4603C|issue=4|arxiv = 0802.3837 }}</ref><ref name="sciencedirect1">{{cite journal|journal=At. Data & Nucl. Data Tables |volume=94|pages=781–806|year=2008|title=Nuclear half-lives for α -radioactivity of elements with 100 ≤ Z ≤ 130|author=Chowdhury, R. P.; Samanta, C.; Basu, D.N.|doi=10.1016/j.adt.2008.01.003|bibcode = 2008ADNDT..94..781C|issue=6|arxiv = 0802.4161 }}</ref> Theoretical calculations done on the synthetic pathways for, and the half-life of, other [[isotopes of ununoctium|isotopes]] have shown that some could be slightly more [[stable isotope|stable]] than the synthesized isotope ²⁹⁴Uuo, most likely ²⁹³Uuo, ²⁹⁵Uuo, ²⁹⁶Uuo, ²⁹⁷Uuo, ²⁹⁸Uuo, ³⁰⁰Uuo and ³⁰²Uuo.<ref name=half-lives/><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|first1=G. |last1=Royer|first2= K. |last2=Zbiri|first3 =C. |last3=Bonilla|doi=10.1016/j.nuclphysa.2003.11.010|arxiv = nucl-th/0410048 |bibcode = 2004NuPhA.730..355R|issue=3–4}}</ref> Of these, ²⁹⁷Uuo might provide the best chances for obtaining longer-lived nuclei,<ref name=half-lives>{{cite journal|journal=Phys. Rev. C|volume=73|page=014612|year=2006|title=α decay half-lives of new superheavy elements|first1=Roy P.|last1=Chowdhury |first2=C. |last2=Samanta |first3= D. N. |last3=Basu|doi=10.1103/PhysRevC.73.014612|arxiv = nucl-th/0507054 |bibcode = 2006PhRvC..73a4612C}}</ref><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 ³¹³Uuo could also provide longer-lived nuclei.<ref>{{cite journal|title=Half-life predictions for decay modes of superheavy nuclei|year=2004|journal=Journal of Physics G: Nuclear and Particle Physics|volume=30|pages=1487–1494|doi=10.1088/0954-3899/30/10/014|first1=S. B.|last1=Duarte|first2=O. A. P.|last2=Tavares|first3=M.|last3=Gonçalves|first4=O.|last4=Rodríguez|first5=F.|last5=Guzmán|first6=T. N.|last6=Barbosa|first7=F.|last7=García|first8=A.|last8=Dimarco|bibcode = 2004JPhG...30.1487D|issue=10}}</ref> ===Calculated atomic and physical properties=== Ununoctium is a member of group 18, the zero-[[valency (chemistry)|valence]] elements. The members of this group are usually inert to most common chemical reactions (for example, combustion) 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 7s²7p⁶ [[electron configuration|configuration]].<ref name=Nash/> Consequently, some expect ununoctium 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|archiveurl = http://web.archive.org/web/20080116172028/http://lenntech.com/Periodic-chart-elements/Uuo-en.htm |archivedate = January 16, 2008|deadurl=yes}}</ref> Following the [[periodic trend]], ununoctium would be expected to be slightly more reactive than radon. However, theoretical calculations have shown that it could be quite reactive, so that it probably cannot be considered a noble gas.<ref name=Kaldor>{{cite book|title=Theoretical Chemistry and Physics of Heavy and Superheavy Elements|first1=Uzi|last1=Kaldor|first2=Stephen|last2=Wilson|page=105|year=2003|publisher=Springer|isbn=1-4020-1371-X}}</ref> In addition to being far more reactive than radon, ununoctium may be even more reactive than elements [[flerovium]] and [[copernicium]].<ref name=Nash>{{cite journal|title=Atomic and Molecular Properties of Elements 112, 114, and 118|first=Clinton S.|last=Nash|journal=Journal of Physical Chemistry A|year=2005|volume=109|issue=15|pages=3493–3500|doi=10.1021/jp050736o|pmid=16833687|last1=Nash|first1=CS}}</ref> The reason for the apparent enhancement of the chemical activity of ununoctium relative to radon is an energetic destabilization and a radial expansion of the last occupied 7p-[[Electron shell#Subshells|subshell]].<ref name=Nash/>{{efn|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 7p_3/2 [[spinor]] shell."}} 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 [[flerovium]], 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|first1=Igor|last1=Goidenko|first2=Leonti|last2=Labzowsky|first3=Ephraim|last3=Eliav|first4=Uzi|last4=Kaldor|first5= Pekka |last5=Pyykko¨|journal=Physical Review A|volume=67|year=2003|pages=020102(R)|doi=10.1103/PhysRevA.67.020102|bibcode = 2003PhRvA..67b0102G|issue=2}}</ref><ref>{{cite journal|volume=77|issue=27|journal=Physical Review Letters|year=1996|title=Element 118: The First Rare Gas with an Electron Affinity|first1=Ephraim |last1=Eliav |first2=Uzi |last2=Kaldor|doi=10.1103/PhysRevLett.77.5350|pages=5350–5352|pmid=10062781|last3=Ishikawa|first3=Y|last4=Pyykkö|first4=P |bibcode=1996PhRvL..77.5350E}}</ref>{{efn|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 element]]s. See Pyykkö.}} 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 from 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&nbsp;K<ref name=Seaborg>{{cite book|title=Modern Alchemy|authorlink=Glenn Theodore Seaborg|first=Glenn Theodore|last=Seaborg|year=1994|isbn=981-02-1440-5|publisher=World Scientific|page =172}}</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|first=N. |last=Takahashi|doi=10.1023/A:1014880730282}}</ref> Even given the large uncertainties of the calculations, it seems highly unlikely that ununoctium would be a gas under [[standard conditions]],<ref name=Nash/>{{efn|It is debatable if the name of the group "noble gases" will be changed if ununoctium is shown to be non-volatile.}} 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 gaseous substances 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 energy]] (similar to that of [[lead]] which is 70% of that of radon<ref name=hydride/> and significantly smaller than that of flerovium<ref>{{cite journal|journal=Journal of Physical Chemistry 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|first=Clinton S.|last=Nash|doi=10.1021/jp982735k|year=1999|last2=Bursten|first2=Bruce E.}}</ref>) and a standard state [[condensed phase]].<ref name=Nash/> ===Predicted compounds=== [[File:Square-planar-3D-balls.png|right|130px|alt=Skeletal model of a planar molecule with a central atom symmetrically bonded to four peripheral (fluorine) atoms.|thumb|[[xenon tetrafluoride|{{chem|Xe||F|4}}]] has a square planar configuration.]] [[File:Tetrahedral-3D-balls.png|right|130px|thumb||alt=Skeletal model of a terahedral molecule with a central atom (Uuo) symmetrically bonded to four peripheral (fluorine) atoms.|{{chem|Uuo||F|4}} is predicted to have a tetrahedral configuration.]] 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)|first=A. V.|last=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> nevertheless, this appears not to be the case.<ref name=BFricke/> Calculations on the [[diatomic molecule]] {{chem|Uuo|2}} showed a [[chemical bond|bonding]] interaction roughly equivalent to that calculated for {{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 0.16 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 predicted to be very limp 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 [[copernicium]] or [[flerovium]].<ref name=hydride/> The stable oxidation states +2 and +4 have been predicted to exist in the [[fluoride]]s {{chem|Uuo||F|2}} and {{chem|Uuo||F|4}}.<ref name=fluoride>{{cite journal|journal=Journal of Physical Chemistry A|volume=103|issue=8|pages=1104–1108|year=1999|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|first1=Young-Kyu|last1=Han|first2=Yoon Sup|last2=Lee|doi=10.1021/jp983665k}}</ref> The +6 state would be less stable due to the strong binding of the 7p_1/2 subshell.<ref name=BFricke>{{cite journal |last1=Fricke |first1=Burkhard |year=1975 |title=Superheavy elements: a prediction of their chemical and physical properties |journal=Recent Impact of Physics on Inorganic Chemistry |volume=21 |pages=89–144 |doi=10.1007/BFb0116498 |url=http://www.researchgate.net/publication/225672062_Superheavy_elements_a_prediction_of_their_chemical_and_physical_properties |accessdate=2013-10-04}}</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 ununoctium 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 T_d configuration]] for {{chem|Uuo||F|4}}, as distinct from the [[square planar|square planar D_4h one]] of [[xenon tetrafluoride|{{chem|Xe||F|4}}]], which {{chem|Rn||F|4}} is also expected to have.<ref name=fluoride/> The Uuo–F bond will most probably be [[ionic bond|ionic]] rather than [[covalent bond|covalent]], rendering the UuoF_''n'' compounds non-volatile.<ref name=Kaldor/><ref>{{cite journal|journal=Journal of the Chemical Society, ChemicalCommunications|year=1975|pages=760–761|doi=10.1039/C3975000760b|title=Fluorides of radon and element 118|first =Kenneth S.|last = Pitzer|issue=18}}</ref> UuoF₂ is predicted to be partially [[ionic bonding|ionic]] due to ununoctium's high [[electropositivity]].<ref name=EB>{{cite web|author=Seaborg|url=http://www.britannica.com/EBchecked/topic/603220/transuranium-element|title=transuranium element (chemical element)|publisher=Encyclopædia Britannica|date=c. 2006|accessdate=2010-03-16}}</ref> Unlike the other noble gases (except possibly [[xenon]]),<ref name="无机化学丛书">{{cite book|title=《无机化学丛书》第一卷：稀有气体、氢、碱金属|pages=P72|author=张青莲|isbn=7-03-002238-6|location=Beijing|publisher=Science Press|date=November 1991}}</ref><ref>{{cite journal|author=Proserpio, Davide M.; Hoffmann, Roald; Janda, Kenneth C.|title=The xenon-chlorine conundrum: van der Waals complex or linear molecule?|year=1991|volume=113|journal=Journal of the American Chemical Society|issue=19|page=7184|doi=10.1021/ja00019a014}}</ref> ununoctium was predicted to be sufficiently electropositive<ref name=EB/> to form a Uuo–Cl bond with [[chlorine]].<ref name=Kaldor/> ==See also== * [[Transactinide element]] * [[Transuranic element]] {{Subject bar |book1=Ununoctium |book2=Period 7 elements |book3=Noble gases |book4=Chemical elements (sorted&nbsp;alphabetically) |book5=Chemical elements (sorted by number) |portal1=Chemistry |portal2=Physics |portal3=Russia |portal4=United States |commons=y |wikt=y |wikt-search=ununoctium |n=y |n-search=Controversy-plagued Element 118, the heaviest atom yet, finally discovered }} ==Notes== {{notes}} ==References== {{clear}} {{Reflist|colwidth=30em}} ==Further reading== * Eric Scerri, ''The Periodic Table, Its Story and Its Significance'', Oxford University Press, New York, 2007. ==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://education.jlab.org/itselemental/ele118.html It's Elemental: Ununoctium] * [http://www.periodicvideos.com/videos/118.htm Ununoctium] at ''[[The Periodic Table of Videos]]'' (University of Nottingham) * [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)] * "[http://query.nytimes.com/gst/fullpage.html?res=9B07E7DB1E30F934A25753C1A9609C8B63 Element 118, Heaviest Ever, Reported for 1,000th of a Second]", NYTimes.com. * [http://www.webelements.com/ununoctium/ WebElements: Ununoctium] {{Compact periodic table}} {{featured article}}'