Editing Nihonium (section)

== Isotopes ==
{{Main|Isotopes of nihonium}}
{{Isotopes summary
|element=nihonium
|reaction ref=<ref name=thoennessen2016>{{Thoennessen2016|pages=229, 234, 238}}</ref>
|isotopes=
{{isotopes summary/isotope
|mn=278 |sym=Nh |hl={{sort|2|2.0 ms}} |ref={{NUBASE2020|ref}}
|dm=α |year=2004 |re=<sup>209</sup>Bi(<sup>70</sup>Zn,n)
}}
{{isotopes summary/isotope
|mn=282 |sym=Nh |hl={{sort|61|61 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>237</sup>Np(<sup>48</sup>Ca,3n)
}}
{{isotopes summary/isotope
|mn=283 |sym=Nh |hl={{sort|123|123 ms}} |ref=<ref name=Mc2022/>
|dm=α |year=2004 |re=<sup>287</sup>Mc(—,α)
}}
{{isotopes summary/isotope
|mn=284 |sym=Nh |hl={{sort|900|0.90 s}} |ref=<ref name=Mc2022/>
|dm=α, EC |year=2004 |re=<sup>288</sup>Mc(—,α)
}}
{{isotopes summary/isotope
|mn=285 |sym=Nh |hl={{sort|2100|2.1 s}} |ref=<ref name=Mc2022/>
|dm=α, SF |year=2010 |re=<sup>289</sup>Mc(—,α)
}}
{{isotopes summary/isotope
|mn=286 |sym=Nh |hl={{sort|9500|9.5 s}} |ref={{NUBASE2020|ref}}
|dm=α |year=2010 |re=<sup>290</sup>Mc(—,α)
}}
{{isotopes summary/isotope
|mn=287 |sym=Nh{{efn|name=nc|This isotope is unconfirmed}} |hl={{sort|5500|5.5 s}} |ref=<ref name="EXON" />
|dm=α |year=1999 |re=<sup>287</sup>Fl(e<sup>−</sup>,ν<sub>e</sub>)
}}
{{isotopes summary/isotope
|mn=290 |sym=Nh{{efn|name=nc}} |hl={{sort|2000|2 s}} |ref=<ref name="Hofmann2016" />
|dm=α |year=1998 |re=<sup>290</sup>Fl(e<sup>−</sup>,ν<sub>e</sub>)
}}}}

Nihonium has no stable or naturally occurring isotopes. Several radioactive isotopes have been synthesised in the laboratory, either by fusing two atoms or by observing the decay of heavier elements. Eight different isotopes of nihonium have been reported with atomic masses 278, 282–287, and 290 (<sup>287</sup>Nh and <sup>290</sup>Nh are unconfirmed); they all decay through alpha decay to isotopes of [[roentgenium]].<ref name="nuclidetable">{{cite web |url=http://www.nndc.bnl.gov/chart/reCenter.jsp?z=113&n=173 |title=Interactive Chart of Nuclides |publisher=Brookhaven National Laboratory |author=Sonzogni, Alejandro |location=National Nuclear Data Center |access-date=6 June 2008 |archive-date=7 August 2007 |archive-url=https://web.archive.org/web/20070807170127/http://www.nndc.bnl.gov/chart/reCenter.jsp?z=113&n=173 |url-status=dead }}</ref> There have been indications that nihonium-284 can also decay by [[electron capture]] to [[copernicium]]-284, though estimates of the [[partial half-life]] for this branch vary strongly by model.<ref>{{cite journal |last1=Forsberg |first1=Ulrika |title=Recoil-α-fission and recoil-α–α-fission events observed in the reaction 48Ca + 243Am |journal=[[Nuclear Physics (journal)|Nuclear Physics A]] |date=September 2016 |volume=953 |pages=117–138 |doi=10.1016/j.nuclphysa.2016.04.025 |bibcode=2016NuPhA.953..117F |arxiv=1502.03030|s2cid=55598355 }}</ref> A [[spontaneous fission]] branch of nihonium-285 has also been reported.<ref name=Mc2022/>

=== Stability and half-lives ===
[[File:Island of Stability derived from Zagrebaev.svg|thumb|upright=1.8|A chart of heavy nuclides with their known and predicted half-lives (known nuclides shown with borders). Nihonium (row 113) is expected to be within the "island of stability" (white circle) and thus its nuclei are slightly more stable than would otherwise be predicted; the known nihonium isotopes are too neutron-poor to be within the island.]]
The stability of nuclei quickly decreases with the increase in atomic number after [[curium]], element 96, whose half-life is over ten thousand times longer than that of any subsequent element. All isotopes with an atomic number above [[mendelevium|101]] undergo radioactive decay with half-lives of less than 30 hours: this is because of the ever-increasing [[Coulomb's law|Coulomb repulsion]] of protons, so that the [[strong nuclear force]] cannot hold the nucleus together against [[spontaneous fission]] for long. Calculations suggest that in the absence of other stabilising factors, elements with more than [[lawrencium|103 protons]] should not exist. Researchers in the 1960s suggested that the closed [[nuclear shell model|nuclear shells]] around 114 protons and 184 neutrons should counteract this instability, and create an "[[island of stability]]" containing nuclides with half-lives reaching thousands or millions of years. The existence of the island is still unproven, but the existence of the [[superheavy element]]s (including nihonium) confirms that the stabilising effect is real, and in general the known superheavy nuclides become longer-lived as they approach the predicted location of the island.<ref>{{cite book |title=Van Nostrand's Scientific Encyclopedia |first1=Douglas M. |last1=Considine |first2=Glenn D. |last2=Considine |publisher=Wiley-Interscience |date=1994 |edition=8th |isbn=978-1-4757-6918-0 |page=623}}</ref><ref name="retro" />

All nihonium isotopes are unstable and radioactive; the heavier nihonium isotopes are more stable than the lighter ones, as they are closer to the centre of the island. The most stable known nihonium isotope, <sup>286</sup>Nh, is also the heaviest; it has a half-life of 8&nbsp;seconds. The isotope <sup>285</sup>Nh, as well as the unconfirmed <sup>287</sup>Nh and <sup>290</sup>Nh, have also been reported to have half-lives of over a second. The isotopes <sup>284</sup>Nh and <sup>283</sup>Nh have half-lives of 0.90 and 0.12&nbsp;seconds respectively. The remaining two isotopes have half-lives between 0.1 and 100&nbsp;milliseconds: <sup>282</sup>Nh has a half-life of 61&nbsp;milliseconds, and <sup>278</sup>Nh, the lightest known nihonium isotope, is also the shortest-lived, with a half-life of 2.0&nbsp;milliseconds. This rapid increase in the half-lives near the closed neutron shell at ''N''&nbsp;=&nbsp;184 is seen in roentgenium, copernicium, and nihonium (elements 111 through 113), where each extra neutron so far multiplies the half-life by a factor of 5 to 20.<ref name="retro">{{cite journal |last1=Oganessian |first1=Yu. Ts. |last2=Sobiczewski |first2=A. |last3=Ter-Akopian |first3=G. M. |date=9 January 2017 |title=Superheavy nuclei: from predictions to discovery |journal=Physica Scripta |volume=92 |issue=2 |pages=023003–1–21 |doi=10.1088/1402-4896/aa53c1 |bibcode=2017PhyS...92b3003O|s2cid=125713877 }}</ref><ref name="Audi">{{NUBASE 2003}}</ref>

The unknown isotopes in the gap between <sup>278</sup>Nh and <sup>282</sup>Nh are too heavy to be produced by cold fusion and too light to be produced by hot fusion. The missing <sup>280</sup>Nh and <sup>281</sup>Nh may be populated as daughters of <sup>284</sup>Mc and <sup>285</sup>Mc, producible in the <sup>241</sup>Am+<sup>48</sup>Ca reaction, but this has not yet been attempted.{{sfn|Zagrebaev|Karpov|Greiner|2013|pp=1–15}} Of particular interest is <sup>281</sup>Nh, as it is the expected great-granddaughter of <sup>293</sup>[[ununennium|119]], a possible product of the <sup>243</sup>Am+<sup>54</sup>Cr reaction.<ref name=jinr2024>{{Cite web |url=https://indico.jinr.ru/event/4343/contributions/28663/attachments/20748/36083/U%20+%20Cr%20AYSS%202024.pptx |title=Synthesis and study of the decay properties of isotopes of superheavy element Lv in Reactions <sup>238</sup>U + <sup>54</sup>Cr and <sup>242</sup>Pu + <sup>50</sup>Ti |last=Ibadullayev |first=Dastan |date=2024 |website=jinr.ru |publisher=[[Joint Institute for Nuclear Research]] |access-date=2 November 2024 |quote=}}</ref> Production of <sup>282</sup>Mc and <sup>283</sup>Mc is possible in the <sup>243</sup>Am+<sup>44</sup>Ca reaction (though it has a lower cross-section), and their daughters would be <sup>278</sup>Nh (known) and <sup>279</sup>Nh.{{sfn|Zagrebaev|Karpov|Greiner|2013|pp=1–15}} The heavier isotopes <sup>287</sup>Nh through <sup>290</sup>Nh might be synthesised using charged-particle evaporation, using the <sup>242</sup>Pu+<sup>48</sup>Ca and <sup>244</sup>Pu+<sup>48</sup>Ca reactions where one proton and some neutrons are evaporated.<ref name=Yerevan2023PPT>{{cite conference |url=https://indico.jinr.ru/event/3622/contributions/20021/attachments/15292/25806/Yerevan2023.pdf |title=Interesting fusion reactions in superheavy region |first1=J. |last1=Hong |first2=G. G. |last2=Adamian |first3=N. V. |last3=Antonenko |first4=P. |last4=Jachimowicz |first5=M. |last5=Kowal |conference=IUPAP Conference "Heaviest nuclei and atoms" |publisher=Joint Institute for Nuclear Research |date=26 April 2023 |access-date=30 July 2023}}</ref><ref name=pxn>{{cite journal |last1=Hong |first1=J. |last2=Adamian |first2=G. G. |last3=Antonenko |first3=N. V. |date=2017 |title=Ways to produce new superheavy isotopes with ''Z''&nbsp;=&nbsp;111–117 in charged particle evaporation channels |journal=Physics Letters B |volume=764 |pages=42–48 |doi=10.1016/j.physletb.2016.11.002 |bibcode=2017PhLB..764...42H|doi-access=free }}</ref>