Editing Seaborgium (section)

==Predicted properties==
Very few properties of seaborgium or its compounds have been measured; this is due to its extremely limited and expensive production<ref name="Bloomberg">{{Cite news|url=https://www.bloomberg.com/news/features/2019-08-28/making-new-elements-doesn-t-pay-just-ask-this-berkeley-scientist|title=Making New Elements Doesn't Pay. Just Ask This Berkeley Scientist|last=Subramanian|first=S.|website=[[Bloomberg Businessweek]]|date=28 August 2019 |access-date=2020-01-18|archive-date=2020-11-14|archive-url=https://archive.today/20201114183428/https://www.bloomberg.com/news/features/2019-08-28/making-new-elements-doesn-t-pay-just-ask-this-berkeley-scientist|url-status=live}}</ref> and the fact that seaborgium (and its parents) decays very quickly. A few singular chemistry-related properties have been measured, but properties of seaborgium metal remain unknown and only predictions are available.

===Physical===
Seaborgium is expected to be a solid under normal conditions and assume a [[body-centered cubic]] crystal structure, similar to its lighter [[congener (chemistry)|congener]] tungsten.<ref name="bcc" /> Early predictions estimated that it should be a very heavy metal with density around 35.0&nbsp;g/cm<sup>3</sup>,<ref name="Haire" /> but calculations in 2011 and 2013 predicted a somewhat lower value of 23–24&nbsp;g/cm<sup>3</sup>.<ref name="density" /><ref name="kratz" />

===Chemical===
Seaborgium is the fourth member of the 6d series of transition metals and the heaviest member of [[group 6 element|group 6]] in the periodic table, below [[chromium]], [[molybdenum]], and [[tungsten]]. All the members of the group form a diversity of oxoanions. They readily portray their group oxidation state of +6, although this is highly oxidising in the case of chromium, and this state becomes more and more stable to reduction as the group is descended: indeed, tungsten is the last of the 5d transition metals where all four 5d electrons participate in [[metallic bonding]].<ref name="Greenwood">{{Greenwood&Earnshaw2nd|pages=1002–39}}</ref> As such, seaborgium should have +6 as its most stable oxidation state, both in the gas phase and in aqueous solution, and this is the only positive oxidation state that is experimentally known for it; the +5 and +4 states should be less stable, and the +3 state, the most common for chromium, would be the least stable for seaborgium.<ref name="Haire" />

This stabilisation of the highest oxidation state occurs in the early 6d elements because of the similarity between the energies of the 6d and 7s orbitals, since the 7s orbitals are relativistically stabilised and the 6d orbitals are relativistically destabilised. This effect is so large in the seventh period that seaborgium is expected to lose its 6d electrons before its 7s electrons (Sg, [Rn]5f<sup>14</sup>6d<sup>4</sup>7s<sup>2</sup>; Sg<sup>+</sup>, [Rn]5f<sup>14</sup>6d<sup>3</sup>7s<sup>2</sup>; Sg<sup>2+</sup>, [Rn]5f<sup>14</sup>6d<sup>3</sup>7s<sup>1</sup>; Sg<sup>4+</sup>, [Rn]5f<sup>14</sup>6d<sup>2</sup>; Sg<sup>6+</sup>, [Rn]5f<sup>14</sup>). Because of the great destabilisation of the 7s orbital, Sg<sup>IV</sup> should be even more unstable than W<sup>IV</sup> and should be very readily oxidised to Sg<sup>VI</sup>. The predicted ionic radius of the hexacoordinate Sg<sup>6+</sup> ion is 65&nbsp;pm, while the predicted atomic radius of seaborgium is 128&nbsp;pm. Nevertheless, the stability of the highest oxidation state is still expected to decrease as Lr<sup>III</sup> &gt; Rf<sup>IV</sup> &gt; Db<sup>V</sup> &gt; Sg<sup>VI</sup>. Some predicted [[standard reduction potential]]s for seaborgium ions in aqueous acidic solution are as follows:<ref name="Haire" />

:{|
|-
| 2 SgO<sub>3</sub> + 2 H<sup>+</sup> + 2 e<sup>−</sup> || {{eqm}} Sg<sub>2</sub>O<sub>5</sub> + H<sub>2</sub>O || E<sup>0</sup> = −0.046 V
|-
| Sg<sub>2</sub>O<sub>5</sub> + 2 H<sup>+</sup> + 2 e<sup>−</sup> || {{eqm}} 2 SgO<sub>2</sub> + H<sub>2</sub>O || E<sup>0</sup> = +0.11 V
|-
| SgO<sub>2</sub> + 4 H<sup>+</sup> + e<sup>−</sup> || {{eqm}} Sg<sup>3+</sup> + 2 H<sub>2</sub>O || E<sup>0</sup> = −1.34 V
|-
| Sg<sup>3+</sup> + e<sup>−</sup> || {{eqm}} Sg<sup>2+</sup> || E<sup>0</sup> = −0.11 V
|-
| Sg<sup>3+</sup> + 3 e<sup>−</sup> || {{eqm}} Sg || E<sup>0</sup> = +0.27 V
|}

Seaborgium should form a very volatile [[hexafluoride]] (SgF<sub>6</sub>) as well as a moderately volatile hexachloride (SgCl<sub>6</sub>), pentachloride (SgCl<sub>5</sub>), and oxychlorides SgO<sub>2</sub>Cl<sub>2</sub> and SgOCl<sub>4</sub>.{{Fricke1975}} SgO<sub>2</sub>Cl<sub>2</sub> is expected to be the most stable of the seaborgium oxychlorides and to be the least volatile of the group 6 oxychlorides, with the sequence MoO<sub>2</sub>Cl<sub>2</sub> &gt; WO<sub>2</sub>Cl<sub>2</sub> &gt; SgO<sub>2</sub>Cl<sub>2</sub>.<ref name="Haire" /> The volatile seaborgium(VI) compounds SgCl<sub>6</sub> and SgOCl<sub>4</sub> are expected to be unstable to decomposition to seaborgium(V) compounds at high temperatures, analogous to MoCl<sub>6</sub> and MoOCl<sub>4</sub>; this should not happen for SgO<sub>2</sub>Cl<sub>2</sub> due to the much higher energy gap between the [[HOMO/LUMO|highest occupied]] and lowest unoccupied [[molecular orbital]]s, despite the similar Sg–Cl bond strengths (similarly to molybdenum and tungsten).<ref name="Kratz">{{cite journal |doi = 10.1351/pac200375010103 |url = https://www.degruyter.com/downloadpdf/j/pac.2003.75.issue-1/pac200375010103/pac200375010103.pdf |title = Critical evaluation of the chemical properties of the transactinide elements (IUPAC Technical Report) |date = 2003 |last1 = Kratz |first1 = J. V. |journal = Pure and Applied Chemistry |volume = 75 |issue = 1 |page = 103 |s2cid = 5172663 |access-date = 2017-02-17 |archive-date = 2017-02-17 |archive-url = https://web.archive.org/web/20170217223948/https://www.degruyter.com/downloadpdf/j/pac.2003.75.issue-1/pac200375010103/pac200375010103.pdf |url-status = live }}</ref>

Molybdenum and tungsten are very similar to each other and show important differences to the smaller chromium, and seaborgium is expected to follow the chemistry of tungsten and molybdenum quite closely, forming an even greater variety of oxoanions, the simplest among them being seaborgate, {{chem|Sg|O|4|2-}}, which would form from the rapid hydrolysis of {{chem|Sg(H|2|O)|6|6+}}, although this would take place less readily than with molybdenum and tungsten as expected from seaborgium's greater size. Seaborgium should hydrolyse less readily than tungsten in [[hydrofluoric acid]] at low concentrations, but more readily at high concentrations, also forming complexes such as SgO<sub>3</sub>F<sup>−</sup> and {{chem|SgOF|5|-}}: complex formation competes with hydrolysis in hydrofluoric acid.<ref name="Haire" />