The correct name for FeO is iron(II) oxide.
This is because FeO consists of iron that is in the +2 oxidation state. In chemical nomenclature, the Roman numeral indicates the oxidation state of the metal. Since iron can have multiple oxidation states, it is important to specify which one is present when naming the compound.
To clarify further, here’s a quick breakdown of the choices:
- Iron oxide is too vague as it does not indicate the oxidation state.
- Iron(II) oxide correctly represents iron with a +2 charge.
- Iron(III) oxide refers to Fe2O3, where iron is in the +3 oxidation state.
- Iron monoxide is not a standard IUPAC name; it would generally be reserved for compounds of the form MO.
- Iron(I) oxide implies a +1 oxidation state, which does not apply for FeO.
Thus, the final and correct designation for FeO is iron(II) oxide.