Editing Copernicium (section)

==Experimental atomic gas phase chemistry==
Interest in copernicium's chemistry was sparked by predictions that it would have the largest relativistic effects in the whole of period&nbsp;7 and group&nbsp;12, and indeed among all 118 known elements.<ref name="Haire" /> Copernicium is expected to have the ground state electron configuration [Rn] 5f<sup>14</sup> 6d<sup>10</sup> 7s<sup>2</sup> and thus should belong to group&nbsp;12 of the periodic table, according to the [[Aufbau principle]]. As such, it should behave as the heavier homologue of [[mercury (element)|mercury]] and form strong binary compounds with [[noble metal]]s like gold. Experiments probing the reactivity of copernicium have focused on the [[adsorption]] of atoms of element&nbsp;112 onto a gold surface held at varying temperatures, in order to calculate an adsorption enthalpy. Owing to relativistic stabilization of the 7s electrons, copernicium shows radon-like properties. Experiments were performed with the simultaneous formation of mercury and radon radioisotopes, allowing a comparison of adsorption characteristics.<ref name="superheavy" />

The first chemical experiments on copernicium were conducted using the <sup>238</sup>U(<sup>48</sup>Ca,3n)<sup>283</sup>Cn reaction. Detection was by spontaneous fission of the claimed parent isotope with half-life of 5&nbsp;minutes. Analysis of the data indicated that copernicium was more volatile than mercury and had noble gas properties. However, the confusion regarding the synthesis of copernicium-283 has cast some doubt on these experimental results.<ref name="superheavy" /> Given this uncertainty, between April–May 2006 at the JINR, a FLNR–PSI team conducted experiments probing the synthesis of this isotope as a daughter in the nuclear reaction <sup>242</sup>Pu(<sup>48</sup>Ca,3n)<sup>287</sup>Fl.<ref name="superheavy" /> (The <sup>242</sup>Pu + <sup>48</sup>Ca fusion reaction has a slightly larger cross-section than the <sup>238</sup>U + <sup>48</sup>Ca reaction, so that the best way to produce copernicium for chemical experimentation is as an overshoot product as the daughter of flerovium.)<ref name="Moody">{{cite book |chapter=Synthesis of Superheavy Elements |last1=Moody |first1=Ken |editor1-first=Matthias |editor1-last=Schädel |editor2-first=Dawn |editor2-last=Shaughnessy |title=The Chemistry of Superheavy Elements |publisher=Springer Science & Business Media |edition=2nd |pages=24–28 |isbn=9783642374661|date=2013}}</ref> In this experiment, two atoms of copernicium-283 were unambiguously identified and the adsorption properties were interpreted to show that copernicium is a more volatile homologue of mercury, due to formation of a weak metal-metal bond with gold.<ref name="superheavy" /> This agrees with general indications from some relativistic calculations that copernicium is "more or less" homologous to mercury.<ref>{{cite web |url=https://tan11.jinr.ru/pdf/07_Sep/S_3/04_Titov.pdf |title=Relativistic DFT and ab initio calculations on the seventh-row superheavy elements: E113 – E114 |last1=Zaitsevskii |first1=A. |first2=C. |last2=van Wüllen |first3=A. |last3=Rusakov |first4=A. |last4=Titov |date=September 2007 |website=jinr.ru |access-date=17 February 2018 |archive-date=18 February 2018 |archive-url=https://web.archive.org/web/20180218023915/http://tan11.jinr.ru/pdf/07_Sep/S_3/04_Titov.pdf |url-status=dead }}</ref> However, it was pointed out in 2019 that this result may simply be due to strong dispersion interactions.<ref name="CRNL" />

In April 2007, this experiment was repeated and a further three atoms of copernicium-283 were positively identified. The adsorption property was confirmed and indicated that copernicium has adsorption properties in agreement with being the heaviest member of group 12.<ref name="superheavy">
{{Cite web
|last1=Gäggeler
|first1=H. W.
|year=2007
|title=Gas Phase Chemistry of Superheavy Elements
|url=https://lch.web.psi.ch/files/lectures/TexasA&M/TexasA&M.pdf
|pages=26–28
|publisher=[[Paul Scherrer Institute]]
|url-status=dead
|archive-url=https://web.archive.org/web/20120220090755/https://lch.web.psi.ch/files/lectures/TexasA%26M/TexasA%26M.pdf
|archive-date=2012-02-20
}}</ref> These experiments also allowed the first experimental estimation of copernicium's boiling point: 84{{su|p=+112|b=−108}}&nbsp;°C, so that it may be a gas at standard conditions.<ref name="Eichler" />

Because the lighter group 12 elements often occur as [[chalcogen]]ide ores, experiments were conducted in 2015 to deposit copernicium atoms on a [[selenium]] surface to form copernicium selenide, CnSe. Reaction of copernicium atoms with trigonal selenium to form a selenide was observed, with -Δ''H''<sub>ads</sub><sup>Cn</sup>(t-Se) > 48&nbsp;kJ/mol, with the kinetic hindrance towards selenide formation being lower for copernicium than for mercury. This was unexpected as the stability of the group 12 selenides tends to decrease down the group from [[Zinc selenide|ZnSe]] to [[Mercury selenide|HgSe]].<ref name="selenide">{{cite web |year=2015 |title=Annual Report 2015: Laboratory of Radiochemistry and Environmental Chemistry |page=3 |publisher=Paul Scherrer Institute |url=https://www.psi.ch/luc/AnnualReportsEN/PSI_LCH_AnnualReport2015.pdf |access-date=2016-12-04 |archive-date=2016-12-20 |archive-url=https://web.archive.org/web/20161220050629/https://www.psi.ch/luc/AnnualReportsEN/PSI_LCH_AnnualReport2015.pdf |url-status=live }}</ref>