Editing Berkelium (section)

===Oxides===
Two oxides of berkelium are known, with the berkelium [[redox|oxidation]] state of +3 ({{chem2|Bk2O3}}) and +4 ([[Berkelium(IV) oxide|{{chem2|BkO2}}]]).<ref>{{cite journal|last1=Peterson|first1=J.|title=Crystal structures and lattice parameters of the compounds of berkelium I. Berkelium dioxide and cubic berkelium sesquioxide|journal=Inorganic and Nuclear Chemistry Letters|volume=3|pages=327|date=1967|doi=10.1016/0020-1650(67)80037-0|issue=9|last2=Cunningham|first2=B. B.|url=https://escholarship.org/uc/item/5mv047vq}}</ref> {{Not a typo|Berkelium(IV)}} oxide is a brown solid,<ref name="BK_OX">{{cite journal|last1=Baybarz|first1=R. D.|title=The berkelium oxide system|journal=Journal of Inorganic and Nuclear Chemistry|volume=30|pages=1769–1773|date=1968|doi=10.1016/0022-1902(68)80352-5|issue=7}}</ref> while {{Not a typo|berkelium(III)}} oxide is a yellow-green solid with a melting point of 1920&nbsp;°C{{sfn|Holleman|Wiberg|2007|p=1972}}<ref name="BK_OX" /> and is formed from BkO<sub>2</sub> by [[redox|reduction]] with molecular [[hydrogen]]:
:{{chem2|2 BkO2 + H2 → Bk2O3 + H2O}}

Upon heating to 1200&nbsp;°C, the oxide {{chem2|Bk2O3}} undergoes a phase change; it undergoes another phase change at 1750&nbsp;°C. Such three-phase behavior is typical for the actinide [[sesquioxide]]s. {{Not a typo|Berkelium(II)}} oxide, BkO, has been reported as a brittle gray solid but its exact chemical composition remains uncertain.{{sfn|Peterson|Hobart|1984|p=51}}