Unbibium എന്ന താളിന്റെ മൂലരൂപം കാണുക

{{Infobox unbibium}}
'''Unbibium''' ({{IPAc-en|icon|uː|n|ˈ|b|ɪ|b|i|ə|m}}), also referred to as '''[[Mendeleev's predicted elements|eka]]'''-'''[[thorium]]''' or element 122, is the temporary name of a currently unknown [[chemical element]] in the [[periodic table]] that has the temporary symbol Ubb and the atomic number 122.

In 2008, it was claimed to have been discovered in natural thorium samples<ref name=arxiv>{{cite journal |last=Marinov |first=A. |coauthors=Rodushkin, I.; Kolb, D.; Pape, A.; Kashiv, Y.; Brandt, R.; Gentry, R. V.; Miller, H. W. |title=Evidence for a long-lived superheavy nucleus with atomic mass number A=292 and atomic number Z=~122 in natural Th |journal= International Journal of Modern Physics E|year=2008 |arxiv=0804.3869 |bibcode = 2010IJMPE..19..131M |doi = 10.1142/S0218301310014662 |volume=19 |pages=131 }}</ref> but that claim has now been dismissed by recent repetitions of the experiment using more accurate techniques.

==History==
===Neutron evaporation===
The first attempt to synthesize unbibium was performed in 1972 by Flerov ''et al.'' at [[JINR]], using the hot fusion reaction:

:<math>\,^{238}_{92}\mathrm{U} + \,^{66}_{30}\mathrm{Zn} \to \,^{304}_{122}\mathrm{Ubb} ^{*} \to \ \mbox{no atoms}.</math>

No atoms were detected and a yield limit of 5 [[Barn (unit)|mb]] (5,000,000 [[barn (unit)|pb]]){{Dubious|reason=5mb=5,000,000,000 pb, so one of the values must be wrong|date=August 2010}} was measured. Current results (see [[flerovium]]) have shown that the sensitivity of this experiment was too low by at least 6 orders of magnitude.{{Citation needed|date=February 2012}}

In 2000, the [[Gesellschaft für Schwerionenforschung]] performed a very similar experiment with much higher sensitivity:

:<math>\,^{238}_{92}\mathrm{U} + \,^{70}_{30}\mathrm{Zn} \to \,^{308}_{122}\mathrm{Ubb} ^{*} \to \ \mbox{no atoms}.</math>

These results indicate that the synthesis of such heavier elements remains a significant challenge and further improvements of beam intensity and experimental efficiency is required. The sensitivity should be increased to 1 [[barn (unit)|fb]].{{Citation needed|date=February 2012}}

===Compound nucleus fission===
Several experiments have been performed between 2000-2004 at the Flerov laboratory of Nuclear Reactions studying the fission characteristics of the compound nucleus <sup>306</sup>Ubb. Two nuclear reactions have been used, namely <sup>248</sup>Cm + <sup>58</sup>Fe and <sup>242</sup>Pu + <sup>64</sup>Ni. The results have revealed how nuclei such as this fission predominantly by expelling [[nuclear shell model|closed shell]] nuclei such as <sup>132</sup>Sn (Z=50, N=82). It was also found that the yield for the fusion-fission pathway was similar between <sup>48</sup>Ca and <sup>58</sup>Fe projectiles, indicating a possible future use of <sup>58</sup>Fe projectiles in superheavy element formation.<ref>see Flerov lab annual reports 2000–2004 inclusive http://www1.jinr.ru/Reports/Reports_eng_arh.html</ref>

===Claimed discovery as a naturally occurring element===
On April 24, 2008, a group led by Amnon Marinov at the [[Hebrew University of Jerusalem]] claimed to have found single atoms of unbibium in naturally occurring [[thorium]] deposits at an abundance of between 10<sup>−11</sup> and 10<sup>−12</sup>, relative to thorium.<ref name=arxiv/> The claim of Marinov ''et al.'' was criticized by a part of the scientific community, and Marinov says he has submitted the article to the journals ''[[Nature (journal)|Nature]]'' and ''[[Nature Physics]]'' but both turned it down without sending it for peer review.<ref>[[Royal Society of Chemistry]], "[http://rsc.org/chemistryworld/News/2008/May/02050802.asp Heaviest element claim criticised] {{Webarchive|url=https://web.archive.org/web/20160304042449/http://rsc.org/chemistryworld/News/2008/May/02050802.asp |date=2016-03-04 }}", Chemical World.</ref>

A criticism of the technique, previously used in purportedly identifying lighter [[thorium]] isotopes by mass spectrometry,<ref name="thorium1">{{cite journal |journal=Phys. Rev. C |title=Existence of long-lived isomeric states in naturally-occurring neutron-deficient Th isotopes |year=2007 |volume=76 |page=021303(R) |doi=10.1103/PhysRevC.76.021303 |author=A. Marinov; I. Rodushkin; Y. Kashiv; L. Halicz; I. Segal; A. Pape; R. V. Gentry; H. W. Miller; D. Kolb; R. Brandt |arxiv = nucl-ex/0605008 |bibcode = 2007PhRvC..76b1303M |issue=2 }}</ref><ref name="thorium2">{{cite journal |arxiv=nucl-ex/0605008 |doi=10.1103/PhysRevC.76.021303 |title=Existence of long-lived isomeric states in naturally-occurring neutron-deficient Th isotopes |year=2007 |author=Marinov, A. |journal=Physical Review C |volume=76 |pages=021303 |last2=Rodushkin |first2=I. |last3=Kashiv |first3=Y. |last4=Halicz |first4=L. |last5=Segal |first5=I. |last6=Pape |first6=A. |last7=Gentry |first7=R. |last8=Miller |first8=H. |last9=Kolb |first9=D. |bibcode = 2007PhRvC..76b1303M |issue=2 }}</ref> was published in Physical Review C in 2008.<ref>{{cite journal |journal=Phys. Rev. C |title=Comment on "Existence of long-lived isomeric states in naturally-occurring neutron-deficient Th isotopes" |year=2009 |volume=79 |pages=049801 |doi=10.1103/PhysRevC.79.049801 |author=R. C. Barber; J. R. De Laeter |bibcode = 2009PhRvC..79d9801B |issue=4 }}</ref> A rebuttal by the Marinov group was published in Physical Review C after the published comment.<ref>{{cite journal |journal=Phys. Rev. C |title=Reply to "Comment on 'Existence of long-lived isomeric states in naturally-occurring neutron-deficient Th isotopes'" |year=2009 |volume=79 |pages=049802 |doi=10.1103/PhysRevC.79.049802 |author=A. Marinov; I. Rodushkin; Y. Kashiv; L. Halicz; I. Segal; A. Pape; R. V. Gentry; H. W. Miller; D. Kolb; R. Brandt |bibcode = 2009PhRvC..79d9802M |issue=4 }}</ref>

A repeat of the thorium-experiment using the superior method of Accelerator Mass Spectrometry (AMS) failed to confirm the results, despite a 100-fold better sensitivity.<ref>{{cite journal |journal=Phys. Rev. C |title=Search for long-lived isomeric states in neutron-deficient thorium isotopes |year=2008 |volume=78 |page= 064313 |doi=10.1103/PhysRevC.78.064313 |author=J. Lachner; I. Dillmann; T. Faestermann; G. Korschinek; M. Poutivtsev; G. Rugel |bibcode = 2008PhRvC..78f4313L |issue=6 }}</ref> This result throws considerable doubt on the results of the Marinov collaboration with regards to their claims of long-lived isotopes of [[thorium]],<ref name="thorium1"/><ref name="thorium2"/> [[roentgenium]]<ref name="roentgenium">{{cite journal |last1=Marinov |first1=A. |last2=Rodushkin |first2=I. |last3=Pape |first3=A. |last4=Kashiv |first4=Y. |last5=Kolb |first5=D. |last6=Brandt |first6=R. |last7=Gentry |first7=R. V. |last8=Miller |first8=H. W. |last9=Halicz |first9=L. |year=2009 |title=Existence of Long-Lived Isotopes of a Superheavy Element in Natural Au |journal=[[International Journal of Modern Physics E]] |volume=18 |number=3 |pages=621–629 |publisher=[[World Scientific Publishing Company]] |doi=  10.1142/S021830130901280X|url=http://www.phys.huji.ac.il/~marinov/publications/Au_paper_IJMPE_73.pdf |accessdate=February 12, 2012 |arxiv = nucl-ex/0702051 |bibcode = 2009IJMPE..18..621M }}</ref> and unbibium.<ref name="arxiv"/>

==Nucleosynthesis==
===Target-projectile combinations leading to Z=122 compound nuclei===
The table below contains various combinations of targets and projectiles which could be used to form compound nuclei with atomic number 122.{{Citation needed|date=February 2012}}

{|class="wikitable" style="text-align:center"
! Target !! Projectile !! CN !! Attempt result
|-
!<sup>238</sup>U
|<sup>70</sup>Zn||<sup>308</sup>Ubb||{{no|Failure to date}}
|-
!<sup>238</sup>U
|<sup>66</sup>Zn||<sup>304</sup>Ubb||{{no|Failure to date}}
|-
!<sup>242</sup>Pu
|<sup>64</sup>Ni||<sup>306</sup>Ubb||{{no|Failure to date}}
|-
!<sup>248</sup>Cm
|<sup>58</sup>Fe||<sup>306</sup>Ubb||{{no|Failure to date}}
|}<!--Please use {{yes|Successful reaction}} for successes, thanks-->

==Chemical properties==
===Electronic structure===
It has been predicted by [[Ephraim Eliav]] ''et al.'' that unbibium will have the electron configuration &#91;[[Ununoctium|Uuo]]&#93;8s<sup>2</sup>7d<sup>1</sup>8p<sup>1</sup>.<ref>{{cite book| title = The Chemistry of the Actinide and Transactinide Elements| editor1-last = Morss|editor2-first = Norman M.| editor2-last = Edelstein| editor3-last = Fuger|editor3-first = Jean| last1 = Hoffman|first1 = Darleane C.| last2=Lee|first2=Diana M. |last3=Pershina|first3=Valeria | chapter = Transactinides and the future elements| publisher = [[Springer Science+Business Media]]| year = 2006| page = 1659| isbn = 1-4020-3555-1| location = Dordrecht, The Netherlands| edition = 3rd| ref = CITEREFHaire2006}}</ref>

===Extrapolated chemical properties===
====Chemistry====
If group reactivity is followed, unbibium should be a reactive metal, more reactive than [[cerium]] or [[thorium]]. Unbibium would most likely form the dioxide, Ubb[[Oxygen|O]]<sub>2</sub>, and trihalides, such as Ubb[[Fluorine|F]]<sub>3</sub> and Ubb[[Chlorine|Cl]]<sub>3</sub>. The predicted oxidation states are III and IV (and perhaps II).{{Citation needed|date=February 2012}}

==See also==
*[[Island of stability]]
*[[Systematic element name]]
*[[unbiunium]]–[[unbitrium]]

==References==
{{Reflist|2}}

==External links==
*[http://www.chemistry-blog.com/2008/04/29/adressing-marinovs-element-122-claim/ Chemistry-Blog: Independent analysis of Marinov’s 122 claim] {{Webarchive|url=https://web.archive.org/web/20121022144533/http://www.chemistry-blog.com/2008/04/29/adressing-marinovs-element-122-claim/ |date=2012-10-22 }}
*[http://www.phys.huji.ac.il/~marinov/index.htm Marinov's Site]

{{Compact extended periodic table}}

[[Category:Chemical elements]]
[[Category:Hypothetical chemical elements]]

[[it:Unbibio]]