Trioxide

Antimony trioxide is the inorganic compound with the formula Sb₂O₃. It is the most important commercial compound of antimony. It is found in nature as the minerals valentinite and senarmontite.

Arsenic trioxide is the inorganic compound with the formula As₂O₃. This commercially important oxide of arsenic is the main precursor to other arsenic compounds, including organoarsenic compounds.

Iron(III) oxide—also known as ferric oxide, ferric iron, hematite, red iron oxide, synthetic maghemite, colcothar, or simply rust—is one of the several oxide compounds of iron, and has paramagnetic properties. Its chemical formula is Fe2O3.

Chromium trioxide is the inorganic compound with the formula CrO3. It is the acid anhydride of chromic acid, and is sometimes marketed under the same name.[1] This compound is a dark red/orange brown solid, which dissolves in water concomitant with hydrolysis.

Boron oxide is one of the oxides of boron. It is white, glassy, and solid, also known as diboron trioxide, formula B2O3. It is almost always found as the vitreous (amorphic) form; however, it can be crystallized after extensive annealing. It is one of the most difficult compounds known to crystallize.