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| {{Infobox unbiquadium}}
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| '''Unbiquadium''' {{IPAc-en|uː|n|b|aɪ|ˈ|k|w|ɒ|d|i|ə|m}}, also known as '''[[Mendeleev's predicted elements|eka]]-[[uranium]]''' or element 124, is the temporary name of a hypothetical [[chemical element|element]] in the [[periodic table]] that has the temporary symbol Ubq and [[atomic number]] 124.
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| In 2008, a team at [[Grand Accélérateur National d'Ions Lourds|GANIL]], France, published results indicating that nuclei of unbiquadium had been produced at very high excitation energy, which underwent fission with measurable lifetimes. This result suggests a strong stabilizing effect at Z=124 and points to the next proton shell at Z>120, not at Z=114 as previously thought.
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| ==Synthesis of unbiquadium nuclei==
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| Scientists at GANIL attempted to measure the direct and delayed fission of compound nuclei of elements with Z=114, 120, and 124 in order to probe [[nuclear shell|shell]] effects in this region and to pinpoint the next spherical proton shell. This is because having complete nuclear shells (or, equivalently, having a [[magic number (physics)|magic number]] of [[proton]]s or [[neutron]]s) would confer more stability on the nuclei of such superheavy elements, thus moving closer to the [[island of stability]]. In 2006, with full results published in 2008, the team provided results from a reaction involving the bombardment of a natural germanium target with uranium ions:
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| :<math>\,^{238}_{92}\mathrm{U} + \,^{nat}_{32}\mathrm{Ge} \to \,^{308,310,311,312,314}\mathrm{Ubq} ^{*} \to \ fission.</math>
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| The team reported that they had been able to identify compound nuclei fissioning with half-lives > 10<sup>−18</sup> s. A compound nucleus is a loose combination of [[nucleon]]s that have not arranged themselves into nuclear shells yet.<ref name=emsley/> It has no internal structure and is held together for its brief existence only by the forces generated during the collision between the target and projectile nuclei. It is estimated that it requires around 10<sup>−14</sup> s for the nucleons to arrange themselves into nuclear shells,<ref name=emsley/> at which point the compound nucleus becomes an [[nuclide]], and this number is used by [[IUPAC]]<ref>http://science.howstuffworks.com/periodic-table5.htm</ref> as the minimum [[half-life]] a claimed isotope must have to potentially be recognised as being discovered. Thus, the GANIL experiments do not count as a discovery of element 124.<ref name="emsley">{{cite book |last=Emsley |first=John |title=Nature's Building Blocks: An A-Z Guide to the Elements |edition=New |year=2011 |publisher=Oxford University Press |location=New York, NY |isbn=978-0-19-960563-7 |page=590}}</ref> Although a half-life of just over 10<sup>−18</sup> seconds is very short, the ability to measure such decays indicated a strong shell effect at Z=124. A similar phenomenon was found for [[unbinilium|Z=120]] but not for [[flerovium]] (Z=114).<ref>{{cite journal |last1=Morjean |first1=M. |last2=Charvet |first2=J.L. |first3=A. |last3=Chbihi |first4=M. |last4=Chevallier |first5=C. |last5=Cohen |first6=D. |last6=Dauvergne |first7=R. |last7=Dayras |first8=A. |last8=Drouart |first9=J.D. |last9=Frankland|first10=D. |last10=Jacquet|first11=R. |last11=Kirsch, |first12=M. |last12=Laget|first13=P. |last13=Lautesse|first14=A. |last14=L'Hoir|first15=A. |last15=Marchix|first16=L. |last16=Nalpas|first17=M. |last17=Parlog|first18=C. |last18=Ray|first19=C. |last19=Schmitt|first20=C. |last20=Stodel|first21=L. |last21=Tassan-Got|first22=C. |last22=Volant|date=February 5, 2007 |title=Direct experimental evidence for very long fission times of super-heavy elements |url=http://hal.archives-ouvertes.fr/docs/00/12/91/31/PDF/WAPHE06_EPJ_preprint1.pdf |accessdate=January 27, 2013}}</ref>
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| ==Name==
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| The name unbiquadium is an [[International Union of Pure and Applied Chemistry|IUPAC]] [[systematic element name]], the temporary name and symbol assigned to newly synthesized and not-yet-synthesized chemical elements. A [[transuranic]] element receives a permanent name and symbol only after its synthesis has been confirmed. Transuranic elements beyond [[californium]] are always artificially produced, and usually end up being named for a scientist or the location of a laboratory that does work in [[atomic physics]].
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| ==References==
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| <references/>
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| {{Compact extended periodic table}}
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| [[Category:Chemical elements]]
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| [[Category:Hypothetical chemical elements]]
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