Editing Polonium (section)

====Compounds====
Polonium has no common compounds, and almost all of its compounds are synthetically created; more than 50 of those are known.<ref>[[#Bagnall|Bagnall]], p. 199</ref> The most stable class of polonium compounds are [[polonide]]s, which are prepared by direct reaction of two elements. [[sodium polonide|Na<sub>2</sub>Po]] has the [[antifluorite]] structure, the polonides of [[calcium polonide|Ca]], [[barium polonide|Ba]], [[mercury polonide|Hg]], Pb and lanthanides form a NaCl lattice, [[beryllium polonide|BePo]] and [[cadmium polonide|CdPo]] have the [[wurtzite]] and [[magnesium polonide|MgPo]] the [[nickel arsenide]] structure. Most polonides decompose upon heating to about 600&nbsp;°C, except for HgPo that decomposes at ~300&nbsp;°C and the [[lanthanide]] polonides, which do not decompose but melt at temperatures above 1000&nbsp;°C. For example, the polonide of [[praseodymium]] (PrPo) melts at 1250&nbsp;°C, and that of [[thulium]] (TmPo) melts at 2200&nbsp;°C.<ref name="g766">[[#Greenwood|Greenwood]], p. 766</ref> [[lead polonide|PbPo]] is one of the very few naturally occurring polonium compounds, as polonium [[alpha decay]]s to form [[lead]].<ref>{{cite journal |last1=Weigel |first1=F. |date=1959 |title=Chemie des Poloniums |journal=[[Angewandte Chemie]] |volume=71 |pages=289–316 |doi=10.1002/ange.19590710902 |issue=9|bibcode=1959AngCh..71..289W }}</ref>

[[Polonium hydride]] ({{chem|Po||H|2}}) is a volatile liquid at room temperature prone to dissociation; it is thermally unstable.<ref name="g766" /> [[properties of water|Water]] is the only other known [[hydrogen chalcogenide]] which is a liquid at room temperature; however, this is due to hydrogen bonding. The three oxides, [[polonium monoxide|PoO]], [[polonium dioxide|PoO<sub>2</sub>]] and [[polonium trioxide|PoO<sub>3</sub>]], are the products of oxidation of polonium.<ref>{{cite book| author = Holleman, A. F.| author2 = Wiberg, E. |title = Inorganic Chemistry| publisher = Academic Press| location = San Diego| date = 2001| isbn = 978-0-12-352651-9}}</ref>

[[Halide]]s of the structure PoX<sub>2</sub>, PoX<sub>4</sub> and PoF<sub>6</sub> are known. They are soluble in the corresponding hydrogen halides, i.e., PoCl<sub>X</sub> in HCl, PoBr<sub>X</sub> in HBr and PoI<sub>4</sub> in HI.<ref name="figgins" /> Polonium dihalides are formed by direct reaction of the elements or by reduction of PoCl<sub>4</sub> with SO<sub>2</sub> and with PoBr<sub>4</sub> with H<sub>2</sub>S at room temperature. Tetrahalides can be obtained by reacting polonium dioxide with HCl, HBr or HI.<ref name="g765">[[#Greenwood|Greenwood]], pp. 765, 771, 775</ref>

Other polonium compounds include the [[polonite]], [[potassium polonite]]; various [[polonate]] solutions; and the [[acetate]], [[bromate]], [[carbonate]], [[citrate]], [[Chromate ion|chromate]], cyanide, [[formate]], [[polonium(II) hydroxide|(II)]] or [[polonium(IV) hydroxide|(IV)]] hydroxide, [[polonium tetranitrate|nitrate]], [[polonium selenate|selenate]], [[polonium selenite|selenite]], monosulfide, [[sulfate]], [[polonium disulfate|disulfate]] or [[polonium sulfite|sulfite]] salts.<ref name="figgins">Figgins, P. E. (1961) [http://www.osti.gov/bridge/purl.cover.jsp?purl=/4034029-SolPsF/ The Radiochemistry of Polonium], National Academy of Sciences, US Atomic Energy Commission, pp. 13–14 [https://books.google.com/books?id=N0MrAAAAYAAJ Google Books]</ref><ref>[[#Bagnall|Bagnall]], pp. 212–226</ref>

A limited [[organopolonium chemistry]] is known, mostly restricted to dialkyl and diaryl polonides (R<sub>2</sub>Po), triarylpolonium halides (Ar<sub>3</sub>PoX), and diarylpolonium dihalides (Ar<sub>2</sub>PoX<sub>2</sub>).<ref name="Z">{{cite book |last=Zingaro |first=Ralph A. |chapter=Polonium: Organometallic Chemistry |date=2011 |title=Encyclopedia of Inorganic and Bioinorganic Chemistry |publisher=John Wiley & Sons |pages=1–3 |doi=10.1002/9781119951438.eibc0182|isbn=9781119951438 }}</ref><ref name="M">{{cite journal |last1=Murin |first1=A. N. |last2=Nefedov |first2=V. D. |first3=V. M. |last3=Zaitsev |first4=S. A. |last4=Grachev |date=1960 |title=Production of organopolonium compounds by using chemical alterations taking place during the β-decay of RaE |url=http://www.mathnet.ru/links/d4bd811f2ded6e2b1d67f43a93e2910e/dan23789.pdf |journal=Dokl. Akad. Nauk SSSR |volume=133 |issue=1 |pages=123–125 |access-date=12 April 2020 |language=ru}}</ref> Polonium also forms soluble compounds with some [[ligand]]s, such as [[2,3-butanediol]] and [[thiourea]].<ref name="Z" />

{|class="wikitable" style="text-align:center"
|+Polonium compounds<ref name="g765" /><ref>Wiberg, Egon; Holleman, A. F. and Wiberg, Nils [https://books.google.com/books?id=Mtth5g59dEIC&pg=PA594 Inorganic Chemistry], Academic Press, 2001, p. 594, {{ISBN|0-12-352651-5}}.</ref>
|-
!Formula!!Color!! [[melting point|m.p.]] (°C)|| [[Sublimation (phase transition)|Sublimation]] <br/>temp. (°C) ||Symmetry||[[Pearson symbol]] || [[Space group]] ||No||a (pm) || b(pm) || c(pm) || Z || [[density|ρ]] (g/cm<sup>3</sup>) ||ref
|-
|[[polonium monoxide|PoO]]|| black|| || || || || || || || || || || ||
|-
|[[polonium dioxide|PoO<sub>2</sub>]]|| pale yellow|| 500 (dec.) ||885 ||[[face-centered cubic|fcc]] ||cF12||Fm{{overline|3}}m ||225 ||563.7||563.7||563.7||4|| 8.94 || <ref name="Bagnall">{{cite journal |last1=Bagnall |first1=K. W. |last2=d'Eye |first2=R. W. M. |date=1954 |title=The Preparation of Polonium Metal and Polonium Dioxide |journal=[[Journal of the Chemical Society|J. Chem. Soc.]] |pages=4295–4299|doi=10.1039/JR9540004295 }}</ref>
|-
|[[polonium hydride|PoH<sub>2</sub>]]|| || -35.5 || || || || || || || || || || ||
|-
|[[polonium dichloride|PoCl<sub>2</sub>]]|| dark ruby red|| 355 ||130 ||[[orthorhombic]] ||oP3||Pmmm||47 ||367||435||450||1|| 6.47 || <ref name="PoCl">{{cite journal|doi=10.1039/JR9550002320|title=The polonium halides. Part I. Polonium chlorides|date=1955|last1=Bagnall|first1=K. W.|last2=d'Eye|first2=R. W. M.|last3=Freeman|first3=J. H.|journal=Journal of the Chemical Society (Resumed)|pages=2320–2326 }}</ref>
|-
|[[polonium dibromide|PoBr<sub>2</sub>]]||purple-brown|| 270 (dec.)|| || || || || || || || || || ||<ref name="PoBr">{{cite journal|doi=10.1039/JR9550003959|title=The polonium halides. Part II. Bromides|date=1955|last1=Bagnall|first1=K. W.|last2=d'Eye|first2=R. W. M.|last3=Freeman|first3=J. H.|journal=Journal of the Chemical Society (Resumed)|pages=3959–3963 }}</ref>
|-
|[[polonium tetrachloride|PoCl<sub>4</sub>]]|| yellow||300 || 200 ||[[monoclinic]] || || || || || || || || ||<ref name="PoCl" />
|-
|[[polonium tetrabromide|PoBr<sub>4</sub>]]|| red||330 (dec.) || ||[[face-centered cubic|fcc]] || cF100 || Fm{{overline|3}}m ||225||560||560||560||4|| || <ref name="PoBr" />
|-
|[[polonium tetraiodide|PoI<sub>4</sub>]]||black || || || || || || || || || || || || <ref>{{cite journal|doi=10.1039/JR9560003385|title=657. The polonium halides. Part III. Polonium tetraiodide|date=1956|last1=Bagnall|first1=K. W.|last2=d'Eye|first2=R. W. M.|last3=Freeman|first3=J. H.|journal=Journal of the Chemical Society (Resumed)|pages=3385–3389 }}</ref>
|}
{{col-begin}}
{{col-break}}
'''Oxides'''
* [[Polonium monoxide|PoO]]
* [[Polonium dioxide|PoO<sub>2</sub>]]
* [[Polonium trioxide|PoO<sub>3</sub>]]
{{col-break}}
'''Hydrides'''
* [[Polonium hydride|PoH<sub>2</sub>]]
{{col-break}}
'''[[Halide]]s'''
* PoX<sub>2</sub> (except PoF<sub>2</sub>)
* PoX<sub>4</sub>
* [[Polonium hexafluoride|PoF<sub>6</sub>]]
* PoBr<sub>2</sub>Cl<sub>2</sub> (salmon pink)
{{col-end}}