* Iron's Variable Oxidation States: Iron can exist in multiple oxidation states, meaning it can lose different numbers of electrons to form ions. The two most common are +2 (ferrous) and +3 (ferric).

* Roman Numerals Indicate Oxidation State: In the systematic naming system, Roman numerals are used within parentheses to specify the oxidation state of a metal when it can form more than one type of ion.

* Determining Oxidation State in Fe₂O₃: In Fe₂O₃, the oxygen atoms each have a -2 charge. Since there are three oxygen atoms (total charge of -6), the two iron atoms must have a total positive charge of +6 to balance it. Therefore, each iron atom has an oxidation state of +3.

* Combining the Information: Because the iron has an oxidation state of +3, the compound is named "iron(III) oxide."

In Summary: The name "iron(III) oxide" clearly indicates that the iron atoms have a +3 oxidation state in this compound.