Editing Tellurium (section)

==Compounds==
{{Main|Tellurium compounds}}
Tellurium belongs to the [[chalcogen]] (group 16) family of elements on the periodic table, which also includes [[oxygen]], [[sulfur]], [[selenium]] and [[polonium]]: Tellurium and selenium compounds are similar. Tellurium exhibits the oxidation states −2, +2, +4 and +6, with +4 being most common.<ref name="lan">{{Cite book|title = The radiochemistry of tellurium|issue = 3038|series = Nuclear science series|publisher = Subcommittee on Radiochemistry, National Academy of Sciences-National Research Council, U.S.|first = G. W.|last = Leddicotte|date = 1961|page = 5|url = http://library.lanl.gov/cgi-bin/getfile?rc000049.pdf|archive-date = 2021-11-06|access-date = 2010-01-28|archive-url = https://web.archive.org/web/20211106195637/https://library.lanl.gov/cgi-bin/getfile?rc000049.pdf|url-status = dead}}</ref>

===Tellurides===

Reduction of Te metal produces the [[Telluride (chemistry)|tellurides]] and polytellurides, Te<sub>n</sub><sup>2−</sup>. The −2 oxidation state is exhibited in binary compounds with many metals, such as [[zinc telluride]], {{chem|ZnTe}}, produced by heating tellurium with zinc.<ref name="roscoe" /> Decomposition of {{chem|ZnTe}} with [[hydrochloric acid]] yields [[hydrogen telluride]] ({{chem|H|2|Te}}), a highly unstable analogue of the other chalcogen hydrides, [[Water (molecule)|{{chem|H|2|O}}]], [[Hydrogen sulfide|{{chem|H|2|S}}]] and [[Hydrogen selenide|{{chem|H|2|Se}}]]:<ref>{{cite book | last=Singh | first=G. | title=Chemistry of lanthanides and actinides | publisher=Discovery Publishing House | publication-place=New Delhi | date=2007 | isbn=978-81-8356-241-6 | oclc=949703811 | page=279}}</ref>
{{block indent|ZnTe + 2 HCl → {{chem|ZnCl|2}} + {{chem|H|2|Te}}}}

===Halides===
The +2 oxidation state is exhibited by the dihalides, {{chem|TeCl|2}}, {{chem|TeBr|2}} and {{chem|TeI|2}}. The dihalides have not been obtained in pure form,<ref name="sykes1990">{{Cite book|title = Advances in Inorganic Chemistry|volume = 35|first = H. J.|last = Emeleus|editor = A. G. Sykes|publisher = Academic Press|date = 1990|isbn = 0-12-023635-4}}</ref>{{rp|274}} although they are known decomposition products of the tetrahalides in organic solvents, and the derived tetrahalotellurates are well-characterized:

{{block indent|Te + {{chem|X|2}} + 2 {{chem|X|-}} → {{chem|TeX|4|2−}}}}

where X is Cl, Br, or I. These anions are [[square planar molecular geometry|square planar]] in geometry.<ref name="sykes1990" />{{rp|281}} Polynuclear anionic species also exist, such as the dark brown {{chem|Te}}{{su|b=2}}{{chem|I|6|2−}},<ref name="sykes1990" />{{rp|283}} and the black {{chem|Te}}{{su|b=4}}{{chem|I|14|2−}}.<ref name="sykes1990" />{{rp|285}}

With fluorine Te forms the [[mixed-valence]] {{chem|Te|2|F|4}} and [[Tellurium hexafluoride|{{chem|TeF|6}}]]. In the +6 oxidation state, the {{chem|–OTeF|5}} structural group occurs in a number of compounds such as [[Teflic acid|{{chem|HOTeF|5}}]], {{chem|B(OTeF|5|)|3}}, {{chem|Xe(OTeF|5|)|2}}, {{chem|Te(OTeF|5|)|4}} and {{chem|Te(OTeF|5|)|6}}.<ref>{{Cite book|chapter = Preparations and Reactions of Inorganic Main-Group Oxide-Fluorides|first1 = John H.|last1 = Holloway|first2 = David|last2 = Laycock|title = Advances in inorganic chemistry and radiochemistry|volume = 27| series = Serial Publication Series|editor = Harry Julius Emeléus|editor2 = A. G. Sharpe|publisher = Academic Press|date = 1983| isbn = 0-12-023627-3|page = 174}}</ref> The [[square antiprism]]atic anion {{chem|TeF|8|2−}} is also attested.<ref name="wiberg2001">{{Cite book|title = Inorganic chemistry|first1 = Egon|last1 = Wiberg|first2 = Arnold Frederick|last2 = Holleman|editor = Nils Wiberg|publisher = Academic Press|date = 2001|isbn = 0-12-352651-5|page = 588|others = translated by Mary Eagleson}}</ref> The other halogens do not form halides with tellurium in the +6 oxidation state, but only tetrahalides ([[Tellurium tetrachloride|{{chem|TeCl|4}}]], [[Tellurium tetrabromide|{{chem|TeBr|4}}]] and [[Tellurium tetraiodide|{{chem|TeI|4}}]]) in the +4 state, and other lower halides ({{chem|Te|3|Cl|2}}, {{chem|Te|2|Cl|2}}, {{chem|Te|2|Br|2}}, {{chem|Te|2|I}} and two forms of {{chem|TeI}}). In the +4 oxidation state, halotellurate anions are known, such as {{chem|TeCl|6|2−}} and {{chem|Te|2|Cl|10|2−}}. Halotellurium cations are also attested, including {{chem|TeI|3|+}}, found in {{chem|TeI|3|AsF|6}}.<ref>{{Cite book|title = Handbook of chalcogen chemistry: new perspectives in sulfur, selenium and tellurium|url = https://archive.org/details/handbookchalcoge00devi_741|url-access = limited|chapter = Recent developments in binary halogen-chalcogen compounds, polyanions and polycations|first = Zhengtao|last = Xu|editor = Francesco A. Devillanova| publisher = Royal Society of Chemistry|date = 2007|isbn = 978-0-85404-366-8|pages = [https://archive.org/details/handbookchalcoge00devi_741/page/n469 457]–466}}</ref>

===Oxocompounds===
[[File:TeO2powder.jpg|thumb|alt=A sample of pale yellow powder|A sample of tellurium dioxide powder]]
Tellurium monoxide was first reported in 1883 as a black amorphous solid formed by the heat decomposition of {{chem|TeSO|3}} in vacuum, disproportionating into [[tellurium dioxide]], {{chem|TeO|2}} and elemental tellurium upon heating.<ref>{{cite encyclopedia|encyclopedia = Encyclopedia of materials, parts, and finishes|title = Tellurium|first = Mel M.|last = Schwartz|edition = 2nd|publisher = CRC Press|date = 2002|isbn = 1-56676-661-3}}</ref><ref name="divers">{{Cite journal|journal = Journal of the Chemical Society|title = On a new oxide of tellurium|first1 = Edward|last1 = Divers|first2 = M.|last2 = Shimosé|volume = 43|doi = 10.1039/CT8834300319|date = 1883|pages = 319–323|url = https://zenodo.org/record/2170636}}</ref> Since then, however, existence in the solid phase is doubted and in dispute, although it is known as a vapor fragment; the black solid may be merely an equimolar mixture of elemental tellurium and tellurium dioxide.<ref name="dutton">{{cite journal |last1 = Dutton |first1 = W. A. |last2 = Cooper |first2 = W. Charles |title = The Oxides and Oxyacids of Tellurium |journal = Chemical Reviews |volume = 66 |pages = 657–675 |date = 1966 |doi = 10.1021/cr60244a003 |issue = 6}}</ref>

Tellurium dioxide is formed by heating tellurium in air, where it burns with a blue flame.<ref name="roscoe">{{Cite book|title = A treatise on chemistry|volume = 1|first1 = Henry Enfield|last1 = Roscoe|author-link1 = Henry Enfield Roscoe|first2 = Carl|author-link2 = Carl Schorlemmer|publisher = Appleton|date = 1878|pages = 367–368|last2 = Schorlemmer}}</ref> Tellurium trioxide, β-{{chem|TeO|3}}, is obtained by thermal decomposition of {{chem|Te(OH)|6}}. The other two forms of trioxide reported in the literature, the α- and γ- forms, were found not to be true oxides of tellurium in the +6 oxidation state, but a mixture of {{chem|Te|4+}}, {{chem|OH|-}} and {{chem|O|2|-}}.<ref name="wickleder">{{Cite book|title = Handbook of chalcogen chemistry: new perspectives in sulfur, selenium and tellurium|url = https://archive.org/details/handbookchalcoge00devi_741|url-access = limited|chapter = Chalcogen-Oxygen Chemistry|first1 = Mathias S.|last1 = Wickleder|editor = Francesco A. Devillanova|publisher = Royal Society of Chemistry|date = 2007|isbn = 978-0-85404-366-8|pages = [https://archive.org/details/handbookchalcoge00devi_741/page/n366 348]–350}}</ref> Tellurium also exhibits mixed-valence oxides, {{chem|Te|2|O|5}} and {{chem|Te|4|O|9}}.<ref name="wickleder" />

The tellurium oxides and hydrated oxides form a series of acids, including [[tellurous acid]] ({{chem|H|2|TeO|3}}), [[telluric acid|orthotelluric acid]] ({{chem|Te(OH)|6}}) and metatelluric acid ({{chem|(H|2|TeO|4|)|''n''}}).<ref name="dutton" /> The two forms of telluric acid form ''[[tellurate]]'' salts containing the TeO{{su|b=4|p=2–}} and TeO{{su|b=6|p=6−}} anions, respectively. Tellurous acid forms ''[[tellurite]]'' salts containing the anion TeO{{su|b=3|p=2−}}.<ref>[[#Greenwood|Greenwood]], p. 748</ref>

===Zintl cations===
[[File:Zintl ion.jpg|thumb|upright=0.5|A solution of {{chem|Te|4|2+}}]]
When tellurium is treated with concentrated sulfuric acid, the result is a red solution of the [[Zintl ion]], {{chem|Te|4|2+}}.<ref name="molnar2009">{{Cite book
| title = Superacid Chemistry
| url = https://archive.org/details/superacidchemist00olah
| url-access = limited
| author1 = Molnar, Arpad 
| author2 = Olah, George Andrew 
| author3 = Surya Prakash, G. K. 
| author4 = Sommer, Jean 
| edition = 2nd
| publisher = Wiley-Interscience
| date = 2009
| isbn = 978-0-471-59668-4
| pages = [https://archive.org/details/superacidchemist00olah/page/n460 444]–445
}}</ref> The oxidation of tellurium by [[arsenic pentafluoride|{{chem|AsF|5}}]] in liquid [[sulfur dioxide|{{chem|SO|2}}]] produces the same [[square planar molecular geometry|square planar]] cation, in addition to the [[trigonal prism]]atic, yellow-orange {{chem|Te|6|4+}}:<ref name="wiberg2001" />

{{block indent|4 Te + 3 {{chem|AsF|5}} → {{chem|Te|4|2+|(AsF|6|-|)|2}} + {{chem|AsF|3}}}}
{{block indent|6 Te + 6 {{chem|AsF|5}} → {{chem|Te|6|4+|(AsF|6|-|)|4}} + 2 {{chem|AsF|3}}}}

Other tellurium Zintl cations include the polymeric {{chem|Te|7|2+}} and the blue-black {{chem|Te|8|2+}}, consisting of two fused 5-membered tellurium rings. The latter cation is formed by the reaction of tellurium with [[tungsten hexachloride]]:<ref name="wiberg2001" />

{{block indent|8 Te + 2 {{chem|WCl|6}} → {{chem|Te|8|2+|(WCl|6|-|)|2}}}}

Interchalcogen cations also exist, such as {{chem|Te|2|Se|6|2+}} (distorted cubic geometry) and {{chem|Te|2|Se|8|2+}}. These are formed by oxidizing mixtures of tellurium and selenium with {{chem|AsF|5}} or [[antimony pentafluoride|{{chem|SbF|5}}]].<ref name="wiberg2001" />

===Organotellurium compounds===
{{Main|Organotellurium chemistry}}
Tellurium does not readily form analogues of [[Alcohol (chemistry)|alcohol]]s and [[thiol]]s, with the functional group –TeH, that are called [[tellurol]]s. The –TeH functional group is also attributed using the prefix ''tellanyl-''.<ref>{{Cite journal|doi = 10.1070/RC1999v068n11ABEH000544|first1 = I. D.|last1 =Sadekov|first2 = A. V.|last2 =Zakharov|title = Stable tellurols and their metal derivatives|journal =Russian Chemical Reviews|date = 1999|volume =68|issue = 11|pages = 909–923|bibcode = 1999RuCRv..68..909S | s2cid=250864006 }}</ref> Like [[Hydrogen telluride|H<sub>2</sub>Te]], these species are unstable with respect to loss of hydrogen. Telluraethers (R–Te–R) are more stable, as are [[telluroxide]]s.<ref>[[#Greenwood|Greenwood]], p. 787</ref>

===Tritelluride quantum materials===

Recently, physicists and materials scientists have been discovering unusual quantum properties associated with layered compounds composed of tellurium that's combined with certain [[rare-earth element]]s, as well as [[yttrium]] (Y).<ref name=Yumigeta1>{{cite journal |last1=Yumigeta |first1=Kentaro |last2=Qin |first2=Ying |last3=Li |first3=Han |last4=Blei |first4=Mark |last5=Attarde |first5=Yashika |last6=Kopas |first6=Cameron |last7=Tongay |first7=Sefaattin |date=2021 |title=Advances in Rare-Earth Tritelluride Quantum Materials: Structure, Properties, and Synthesis |url=https://www.osti.gov/servlets/purl/1816430 |journal=Advanced Science |volume=8 |issue= 12|pages=2004762 |doi=10.1002/advs.202004762 |pmid=34165898 |pmc=8224454 |osti=1816430 |access-date=12 June 2022}}</ref>

These novel materials have the general formula of ''R'' Te<sub>3</sub>, where "''R'' " represents a rare-earth lanthanide (or Y), with the full family consisting of ''R'' = Y, [[lanthanum]] (La), [[cerium]] (Ce), [[praseodymium]] (Pr), [[neodymium]] (Nd), [[samarium]] (Sm), [[gadolinium]] (Gd), [[terbium]] (Tb), [[dysprosium ]] (Dy), [[holmium]] (Ho), [[erbium]] (Er), and [[thulium]] (Tm). Compounds containing [[promethium]] (Pm), [[europium]] (Eu), [[ytterbium]] (Yb), and [[lutetium]] (Lu) have not yet been observed. These materials have a two-dimensional character within an [[orthorhombic crystal system#Two-dimensional|orthorhombic]] crystal structure, with slabs of ''R'' Te separated by sheets of pure tellurium.<ref name=Yumigeta1/>

It is thought that this 2-D layered structure is what leads to a number of interesting quantum features, such as [[charge-density wave]]s, [[electron mobility|high carrier mobility]], [[superconductivity]] under specific conditions, and other peculiar properties whose natures are only now emerging.<ref name=Yumigeta1/>

For example, in 2022, a small group of physicists at [[Boston College]] in Massachusetts led an international team that used optical methods to demonstrate a novel axial mode of a [[Higgs boson|Higgs-]]like particle in ''R'' Te<sub>3</sub> compounds that incorporate either of two rare-earth elements (''R'' = La, Gd).<ref name=Wang1>{{cite journal |last1=Wang |first1=Yiping |last2=Petrides |first2=Ioannis |last3=McNamara |first3=Grant |last4=Hosen |first4=Md Mofazzel |last5=Lei |first5=Shiming |last6=Wu |first6=Yueh-Chun |last7=Hart |first7=James L. |last8=Lv |first8=Hongyan |last9=Yan |first9=Jun |last10=Xiao |first10=Di |last11=Cha |first11=Judy J.|author11-link=Judy Cha |last12=Narang |first12=Prineha |last13=Schoop |first13=Leslie M. |last14=Burch |first14=Kenneth S. |date=8 June 2022 |title=Axial Higgs mode detected by quantum pathway interference in ''R'' Te<sub>3</sub> |url=https://www.nature.com/articles/s41586-022-04746-6 |journal=Nature |volume= 606|issue= 7916|pages= 896–901|doi=10.1038/s41586-022-04746-6 |pmid=35676485 |arxiv=2112.02454 |bibcode=2022Natur.606..896W |s2cid=244908655 |access-date=12 June 2022}}</ref> This long-hypothesized, axial, Higgs-like particle also shows magnetic properties and may serve as a candidate for [[dark matter]].<ref name=Lea1>{{cite news |last=Lea |first=Robert |date=8 June 2022 |title=Physicists discover never-before seen particle sitting on a tabletop |url=https://www.livescience.com/magnetic-higgs-relative-discovered |work= |location=[[Live Science]] |access-date=12 June 2022}}</ref>