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.
List of trioxides
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
References