Editing Meitnerium (section)

==Isotopes==
{{Main|Isotopes of meitnerium}}

Meitnerium has no stable or naturally occurring isotopes. Several radioactive isotopes have been synthesized in the laboratory, either by fusing two atoms or by observing the decay of heavier elements. Eight different isotopes of meitnerium have been reported with [[mass number]]s 266, 268, 270, and 274–278, two of which, meitnerium-268 and meitnerium-270, have unconfirmed [[metastable state]]s. A ninth isotope with mass number 282 is unconfirmed. Most of these decay predominantly through alpha decay, although some undergo spontaneous fission.<ref name="nuclidetable">{{cite web|url=http://www.nndc.bnl.gov/chart/reCenter.jsp?z=109&n=169|title=Interactive Chart of Nuclides|publisher=Brookhaven National Laboratory|author=Sonzogni, Alejandro|location=National Nuclear Data Center|access-date=2008-06-06|archive-date=March 7, 2018|archive-url=https://web.archive.org/web/20180307082344/http://www.nndc.bnl.gov/chart/reCenter.jsp?z=109&n=169|url-status=dead}}</ref>

===Stability and half-lives===
{{Isotopes summary
|element=meitnerium
|reaction ref=<ref name=thoennessen2016>{{Thoennessen2016|pages=229, 234, 238}}</ref>
|isotopes=
{{isotopes summary/isotope
|mn=266 |sym=Mt |hl={{sort|2|2.0 ms}} |ref={{NUBASE2020|ref}}
|dm=α, SF |year=1982 |re=<sup>209</sup>Bi(<sup>58</sup>Fe,n)
}}
{{isotopes summary/isotope
|mn=268 |sym=Mt |hl={{sort|23|23 ms}} |ref={{NUBASE2020|ref}}
|dm=α |year=1994 |re=<sup>272</sup>Rg(—,α)
}}
{{isotopes summary/isotope
|mn=270 |sym=Mt |hl={{sort|800|800 ms}} |ref={{NUBASE2020|ref}}
|dm=α |year=2004 |re=<sup>278</sup>Nh(—,2α)
}}
{{isotopes summary/isotope
|mn=274 |sym=Mt |hl={{sort|640|640 ms}} |ref=<ref name=Mc2022>{{Cite journal |title=New isotope <sup>286</sup>Mc produced in the <sup>243</sup>Am+<sup>48</sup>Ca reaction |last1=Oganessian |first1=Yu. Ts. |last2=Utyonkov |first2=V. K. |last3=Kovrizhnykh |first3=N. D. |display-authors=et al. |date=2022 |journal=Physical Review C |volume=106 |number=64306 |page=064306 |doi=10.1103/PhysRevC.106.064306|bibcode=2022PhRvC.106f4306O |s2cid=254435744 |doi-access=free }}</ref>
|dm=α |year=2006 |re=<sup>282</sup>Nh(—,2α)
}}
{{isotopes summary/isotope
|mn=275 |sym=Mt |hl={{sort|20|20 ms}} |ref=<ref name=Mc2022/>
|dm=α |year=2003 |re=<sup>287</sup>Mc(—,3α)
}}
{{isotopes summary/isotope
|mn=276 |sym=Mt |hl={{sort|620|620 ms}} |ref=<ref name=Mc2022/>
|dm=α |year=2003 |re=<sup>288</sup>Mc(—,3α)
}}
{{isotopes summary/isotope
|mn=277 |sym=Mt |hl={{sort|5|5 ms}} |ref=<ref name="shesummary">{{cite journal|last=Oganessian|first=Y.T.|date=2015|title=Super-heavy element research|url=https://www.researchgate.net/publication/273327193|journal=Reports on Progress in Physics|volume=78|issue=3|pages=036301|doi=10.1088/0034-4885/78/3/036301|pmid=25746203|bibcode=2015RPPh...78c6301O|s2cid=37779526 }}</ref>
|dm=SF |year=2012 |re=<sup>293</sup>Ts(—,4α)
}}
{{isotopes summary/isotope
|mn=278 |sym=Mt |hl={{sort|4500|4.5 s}} |ref=<ref name="shesummary" />
|dm=α |year=2010 |re=<sup>294</sup>Ts(—,4α)
}}
{{isotopes summary/isotope
|mn=282 |sym=Mt{{efn|name=nc|This isotope is unconfirmed}} |hl={{sort|66000|67 s}} |ref=<ref name="Hofmann2016" />
|dm=α |year=1998 |re=<sup>290</sup>Fl(e<sup>−</sup>,ν<sub>e</sub>2α)
}}}}

All meitnerium isotopes are extremely unstable and radioactive; in general, heavier isotopes are more stable than the lighter. The most stable known meitnerium isotope, <sup>278</sup>Mt, is also the heaviest known; it has a half-life of 4.5&nbsp;seconds. The unconfirmed <sup>282</sup>Mt is even heavier and appears to have a longer half-life of 67&nbsp;seconds. With a half-life of 0.8&nbsp;seconds, the next most stable known isotope is <sup>270</sup>Mt.{{NUBASE2020|ref}} The isotopes <sup>276</sup>Mt and <sup>274</sup>Mt have half-lives of 0.62 and 0.64&nbsp;seconds respectively.<ref name=Mc2022/>

The isotope <sup>277</sup>Mt, created as the final decay product of <sup>293</sup>Ts for the first time in 2012, was observed to undergo [[spontaneous fission]] with a half-life of 5 milliseconds. Preliminary data analysis considered the possibility of this fission event instead originating from <sup>277</sup>Hs, for it also has a half-life of a few milliseconds, and could be populated following undetected [[electron capture]] somewhere along the decay chain.<ref name="2012e117">{{Cite journal | last1 = Oganessian | first1 = Yuri Ts. | last2 = Abdullin | first2 = F. Sh. | last3 = Alexander | first3 = C. | last4 = Binder | first4 = J. | last5 = Boll | first5 = R. A. | last6 = Dmitriev | first6 = S. N. | last7 = Ezold | first7 = J. | last8 = Felker | first8 = K. | last9 = Gostic | first9 = J. M. | title = Experimental studies of the <sup>249</sup>Bk + <sup>48</sup>Ca reaction including decay properties and excitation function for isotopes of element 117, and discovery of the new isotope <sup>277</sup>Mt | doi = 10.1103/PhysRevC.87.054621 | journal = Physical Review C | publisher = American Physical Society | volume = 87 <!--| issue = 5 -->| pages = 054621 | number = 54621 | date = 2013-05-30 | bibcode = 2013PhRvC..87e4621O | display-authors = et al.| doi-access = free }}</ref><ref name="2019e117">{{cite journal |last1=Khuyagbaatar |first1=J. |last2=Yakushev |first2=A. |last3=Düllmann |first3=Ch.E. |last4=Ackermann |first4=D. |last5=Andersson |first5=L.-L. |last6=Asai |first6=M. |last7=Block |first7=M. |last8=Boll |first8=R.A. |last9=Brand |first9=H. |display-authors=et al. |date=2019 |title=Fusion reaction <sup>48</sup>Ca+<sup>249</sup>Bk leading to formation of the element Ts (''Z'' = 117) |journal=Physical Review C |volume=99 |issue=5 |pages=054306–1–054306–16 |url=https://jyx.jyu.fi/bitstream/handle/123456789/63921/1/khuyagbaatarym.pdf |doi=10.1103/PhysRevC.99.054306 |bibcode=2019PhRvC..99e4306K |doi-access=free |access-date=June 8, 2019 |archive-date=June 8, 2019 |archive-url=https://web.archive.org/web/20190608194723/https://jyx.jyu.fi/bitstream/handle/123456789/63921/1/khuyagbaatarym.pdf |url-status=live }}</ref> This possibility was later deemed very unlikely based on observed [[decay energy|decay energies]] of <sup>281</sup>Ds and <sup>281</sup>Rg and the short half-life of <sup>277</sup>Mt, although there is still some uncertainty of the assignment.<ref name="2019e117" /> Regardless, the rapid fission of <sup>277</sup>Mt and <sup>277</sup>Hs is strongly suggestive of a region of instability for superheavy nuclei with [[neutron number|''N'']]&nbsp;=&nbsp;168–170. The existence of this region, characterized by a decrease in [[fission barrier]] height between the deformed [[nuclear shell model|shell closure]] at ''N''&nbsp;=&nbsp;162 and spherical shell closure at ''N''&nbsp;=&nbsp;184, is consistent with theoretical models.<ref name="2012e117" />