Editing Curium (section)

===Oxides===
Curium readily reacts with oxygen forming mostly Cm<sub>2</sub>O<sub>3</sub> and CmO<sub>2</sub> oxides,<ref name="lenntech" /> but the divalent oxide CmO is also known.<ref name="HOWI_1972">Holleman, p. 1972</ref> Black CmO<sub>2</sub> can be obtained by burning curium [[oxalate]] ({{chem|Cm|2|(C|2|O|4|)|3}}), nitrate ({{chem|Cm|(N|O|3|)|3}}), or hydroxide in pure oxygen.<ref name="asprey" /><ref name="g1268">Greenwood, p. 1268</ref> Upon heating to 600–650&nbsp;°C in vacuum (about 0.01&nbsp;[[Pascal (unit)|Pa]]), it transforms into the whitish Cm<sub>2</sub>O<sub>3</sub>:<ref name="asprey">{{cite journal|last1=Asprey|first1=L. B.|title=Evidence for Quadrivalent Curium: X-Ray Data on Curium Oxides1|last2=Ellinger|first2=F. H.|last3=Fried|first3=S.|last4=Zachariasen|first4=W. H.|journal=Journal of the American Chemical Society|volume=77|issue=6|page=1707|date=1955|doi=10.1021/ja01611a108|bibcode=1955JAChS..77.1707A }}</ref><ref>{{cite journal|last1=Noe|first1=M.|title=Self-radiation effects on the lattice parameter of 244CmO2|journal=Inorganic and Nuclear Chemistry Letters|volume=7|issue=5|page=421|date=1971|doi=10.1016/0020-1650(71)80177-0|last2=Fuger|first2=J.}}</ref>
: <chem>4CmO2 ->[\Delta T] 2Cm2O3 + O2</chem>.

Or, Cm<sub>2</sub>O<sub>3</sub> can be obtained by reducing CmO<sub>2</sub> with molecular [[hydrogen]]:<ref>{{cite journal|last1=Haug|first1=H.|title=Curium sesquioxide Cm2O3|journal=Journal of Inorganic and Nuclear Chemistry|volume=29|issue=11|page=2753|date=1967|doi=10.1016/0022-1902(67)80014-9}}</ref>
: <chem>2CmO2 + H2 -> Cm2O3 + H2O</chem>

Also, a number of ternary oxides of the type M(II)CmO<sub>3</sub> are known, where M stands for a divalent metal, such as barium.<ref>{{cite journal|last1=Fuger|first1=J.|last2=Haire|first2=R.|last3=Peterson|first3=J.|title=Molar enthalpies of formation of BaCmO3 and BaCfO3|journal=Journal of Alloys and Compounds|volume=200|issue=1–2|page=181|date=1993|doi=10.1016/0925-8388(93)90491-5|url=https://zenodo.org/record/1258637}}</ref>

Thermal oxidation of trace quantities of curium hydride (CmH<sub>2–3</sub>) has been reported to give a volatile form of CmO<sub>2</sub> and the volatile trioxide CmO<sub>3</sub>, one of two known examples of the very rare +6 state for curium.<ref name="CmO3" /> Another observed species was reported to behave similar to a supposed plutonium tetroxide and was tentatively characterized as CmO<sub>4</sub>, with curium in the extremely rare +8 state;<ref name="CmO4">{{cite journal |last1=Domanov |first1=V. P. |date=January 2013 |title=Possibility of generation of octavalent curium in the gas phase in the form of volatile tetraoxide CmO<sub>4</sub> |journal=Radiochemistry |volume=55 |issue=1 |pages=46–51 |doi=10.1134/S1066362213010098 |bibcode=2013Radch..55...46D |s2cid=98076989 }}</ref> but new experiments seem to indicate that CmO<sub>4</sub> does not exist, and have cast doubt on the existence of PuO<sub>4</sub> as well.<ref>{{cite journal|last1=Zaitsevskii|first1=Andréi|last2=Schwarz|first2=W. H. Eugen|date=April 2014|title=Structures and stability of AnO4 isomers, An = Pu, Am, and Cm: a relativistic density functional study.|journal=Physical Chemistry Chemical Physics|volume=2014|issue=16|pages=8997–9001|bibcode=2014PCCP...16.8997Z|doi=10.1039/c4cp00235k|pmid=24695756}}<!--|access-date=March 8, 2015--></ref>