Editing Extended periodic table (section)

==== Unbibium (E122) <span class="anchor" id="Unbibium"></span> ====
The first attempts to synthesize [[unbibium|element 122]] (unbibium) were performed in 1972 by [[Georgy Flerov|Flerov]] et al. at the [[Joint Institute for Nuclear Research]] (JINR), using the heavy-ion induced hot fusion reactions:<ref name="emsley"/>

:{{nuclide|uranium|238}} + {{nuclide|zinc|66,68}} → <sup>304, 306</sup>122* → no atoms

These experiments were motivated by early predictions on the existence of an [[island of stability]] at ''N''&nbsp;=&nbsp;184 and ''Z''&nbsp;>&nbsp;120. No atoms were detected and a yield limit of 5&nbsp;[[Barn (unit)|nb]] (5,000&nbsp;[[barn (unit)|pb]]) was measured. Current results (see [[flerovium]]) have shown that the sensitivity of these experiments were too low by at least 3 orders of magnitude.<ref name=superlourds>{{cite journal|last1=Epherre|first1=M.|last2=Stephan|first2=C.|date=1975|title=Les éléments superlourds|language=fr|journal=Le Journal de Physique Colloques|volume=11|issue=36|pages=C5–159–164|url=https://core.ac.uk/download/pdf/46775464.pdf|doi=10.1051/jphyscol:1975541}}</ref>

In 2000, the [[Gesellschaft für Schwerionenforschung]] (GSI) Helmholtz Center for Heavy Ion Research performed a very similar experiment with much higher sensitivity:<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=588}}</ref>

:{{nuclide|uranium|238}} + {{nuclide|zinc|70}} → <sup>308</sup>122* → no atoms

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&nbsp;[[barn (unit)|fb]] in the future for better quality results.

Another unsuccessful attempt to synthesize element 122 was carried out in 1978 at the GSI Helmholtz Center, where a natural [[erbium]] target was bombarded with [[xenon-136]] ions:<ref name="emsley"/>

:{{nuclide|erbium|''nat''}} + {{nuclide|xenon|136}} → <sup>298, 300, 302, 303, 304, 306</sup>122* → no atoms

In particular, the reaction between <sup>170</sup>Er and <sup>136</sup>Xe was expected to yield alpha-emitters with half-lives of microseconds that would decay down to isotopes of [[flerovium]] with half-lives perhaps increasing up to several hours, as flerovium is predicted to lie near the center of the [[island of stability]]. After twelve hours of irradiation, nothing was found in this reaction. Following a similar unsuccessful attempt to synthesize element 121 from <sup>238</sup>U and <sup>65</sup>Cu, it was concluded that half-lives of superheavy nuclei must be less than one microsecond or the cross sections are very small.<ref name=EndPT>{{cite book|last=Hofmann|first=Sigurd|title=On Beyond Uranium: Journey to the End of the Periodic Table|year=2014|publisher=CRC Press|isbn=978-0415284950|page=[https://archive.org/details/onbeyonduraniumj0000hofm/page/105 105]|url=https://archive.org/details/onbeyonduraniumj0000hofm/page/105}}</ref> More recent research into synthesis of superheavy elements suggests that both conclusions are true.<ref name=Zagrebaev/><ref name=Karpov>{{cite web |url=http://cyclotron.tamu.edu/she2015/assets/pdfs/presentations/Karpov_SHE_2015_TAMU.pdf |title=Superheavy Nuclei: which regions of nuclear map are accessible in the nearest studies |last1=Karpov |first1=A |last2=Zagrebaev |first2=V |last3=Greiner |first3=W |date=2015 |website=cyclotron.tamu.edu |publisher=Texas A & M University |access-date=30 October 2018}}</ref> The two attempts in the 1970s to synthesize element 122 were both propelled by the research investigating whether superheavy elements could potentially be naturally occurring.<ref name="emsley"/>

Several experiments studying the fission characteristics of various superheavy compound nuclei such as <sup>306</sup>122* were performed between 2000 and 2004 at the [[Flerov Laboratory of Nuclear Reactions]]. Two nuclear reactions were used, namely <sup>248</sup>Cm + <sup>58</sup>Fe and <sup>242</sup>Pu + <sup>64</sup>Ni.<ref name="emsley"/> The results reveal how superheavy nuclei fission predominantly by expelling [[nuclear shell model|closed shell]] nuclei such as <sup>132</sup>Sn (''Z''&nbsp;=&nbsp;50, ''N''&nbsp;=&nbsp;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, suggesting a possible future use of <sup>58</sup>Fe projectiles in superheavy element formation.<ref name="www1.jinr.ru">see Flerov lab annual reports 2000–2004 inclusive http://www1.jinr.ru/Reports/Reports_eng_arh.html</ref>