Iron(II,III) oxide
Iron(II,III) oxide is one of the iron oxides, chemical compounds made of iron and oxygen. It is found in nature as the mineral magnetite. It can be a black powder or brittle black solid. Magnetite mining is one of the world's main sources of iron.
A reaction with chemicals like water or oxygen makes it change into red iron(III) oxide over time.
Magnetite is attracted to magnets, and can be made into a permanent magnet. Some magnetite is naturally magnetic, and is called lodestone. The first magnets found by people were made of magnetite, and magnetism is named after it. Though people made better materials like alnico to make stronger magnets, magnetite is still used in a lot of magnets and other electronics because it is cheap. The black color of old cassette tapes and floppy disks is because of a thin layer of magnetite powder on the plastic tape used to store information.
Chemistry
changeThe chemical name iron(II,III) oxide refers to two different kinds of iron in the compound. Iron is a transition metal, so it has multiple different oxidation states depending on the number of missing electrons around the nucleus. Iron(II,III) oxide is a mixture of iron in its +2 (missing two electrons) and +3 (missing three electrons) states: one third of the iron is in the +2 state, and two thirds are in the +3 state.
The chemical formula is Fe
3O
4, meaning that in pure magnetite, there are three iron atoms for every four oxygen atoms. To better show the two different oxidation states of the iron, the formula is also sometimes written as FeO · Fe
2O
3 or Fe2+Fe3+
2O
4.
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