The chemical formula Fe2(SO3)3 is used to represent the compound iron(III) sulfite, which is also known as ferrous sulfite. The compound contains two atoms of iron, three atoms of sulfur and nine atoms of oxygen.
Iron(III) sulfite is composed of two ions of iron(III) and three ions of sulfite. The Roman numerals in the name indicate the charge carried by the iron ion as +3, for a total charge of +6 resulting from the iron(III) in the molecule. The sulfite ion carries a charge of -2, for a combined sulfite charge in the molecule of -6. The charges of both ions balance out in the iron(III) sulfite to give the molecule a neutral charge.