{{Short description|Compound with three oxygen atoms}} {{For|the triple-oxygen-molecule existing in the atmosphere|Ozone}} A '''trioxide''' is a compound with three oxygen atoms. For metals with the M<sub>2</sub>O<sub>3</sub> formula there are several common structures. Al<sub>2</sub>O<sub>3</sub>, Cr<sub>2</sub>O<sub>3</sub>, Fe<sub>2</sub>O<sub>3</sub>, and V<sub>2</sub>O<sub>3</sub> adopt the corundum structure. Many rare earth oxides adopt the "A-type rare earth structure" which is hexagonal. Several others plus indium oxide adopt the "C-type rare earth structure", also called "bixbyite", which is cubic and related to the fluorite structure.<ref name=Jaffe>{{cite book|last=Jaffe|first=Howard W.|title=Crystal Chemistry and Refractivity|year=1996|publisher=Courier Dover Publications|isbn=978-0-486-69173-2|pages=266–272|url=https://books.google.com/books?id=lbxUYhC5YEEC&dq=bixbyite+crystal+structure&pg=PA274|access-date=2021-12-05|archive-date=2023-09-08|archive-url=https://web.archive.org/web/20230908040812/https://books.google.com/books?id=lbxUYhC5YEEC&dq=bixbyite+crystal+structure&pg=PA274|url-status=live}}</ref>

==List of trioxides== <!-- To do: make a wikitable with more info (structure at least) --> ===MO<sub>3</sub>===

*Carbon trioxide, CO<sub>3</sub> *Chromium trioxide, CrO<sub>3</sub> *Molybdenum trioxide, MoO<sub>3</sub> *Rhenium trioxide, ReO<sub>3</sub> *Selenium trioxide, SeO<sub>3</sub> *Sulfur trioxide, SO<sub>3</sub> *Tellurium trioxide, TeO<sub>3</sub> *Tungsten trioxide, WO<sub>3</sub> *Uranium trioxide, UO<sub>3</sub> *Xenon trioxide, XeO<sub>3</sub>

===M<sub>2</sub>O<sub>3</sub>===

*Antimony trioxide, Sb<sub>2</sub>O<sub>3</sub> *Arsenic trioxide, As<sub>2</sub>O<sub>3</sub> *Bismuth(III) oxide, Bi<sub>2</sub>O<sub>3</sub> *Boron trioxide, B<sub>2</sub>O<sub>3</sub> *Cobalt(III) oxide, Co<sub>2</sub>O<sub>3</sub> *Dichlorine trioxide, Cl<sub>2</sub>O<sub>3</sub> *Dinitrogen trioxide, N<sub>2</sub>O<sub>3</sub> *Gadolinium oxide, Gd<sub>2</sub>O<sub>3</sub> *Gallium(III) oxide, Ga<sub>2</sub>O<sub>3</sub> *Gold trioxide, Au<sub>2</sub>O<sub>3</sub> *Indium(III) oxide, In<sub>2</sub>O<sub>3</sub> *Iron(III) oxide, Fe<sub>2</sub>O<sub>3</sub> *Manganese(III) oxide, Mn<sub>2</sub>O<sub>3</sub> *Nickel(III) oxide, Ni<sub>2</sub>O<sub>3</sub> *Phosphorus trioxide, P<sub>4</sub>O<sub>6</sub> (named before the true formula known) *Thallium(III) oxide, Tl<sub>2</sub>O<sub>3</sub> *Terbium(III) oxide, Tb<sub>2</sub>O<sub>3</sub> *Trioxidane, H<sub>2</sub>O<sub>3</sub> *Vanadium trioxide, V<sub>2</sub>O<sub>3</sub> *Ytterbium(III) oxide, Yb<sub>2</sub>O<sub>3</sub> *Yttrium(III) oxide, Y<sub>2</sub>O<sub>3</sub>

===Other trioxides===

*Mineral trioxide aggregate *Sulfur trioxide pyridine complex, SO<sub>3</sub>(py)

==References==

{{reflist}}

Category:Oxides