* Iron(III): The Roman numeral "III" indicates that the iron ion has a +3 charge (Fe³⁺). This is because sulfate (SO₄²⁻) has a -2 charge, and to balance the charges in the compound, two iron ions (2 x +3 = +6) are needed to match the charge of three sulfate ions (3 x -2 = -6).
* Sulfate: The polyatomic ion SO₄²⁻ is called sulfate.
Therefore, the systematic name combines the metal cation name with its charge (as a Roman numeral) and the polyatomic anion name: Iron(III) Sulfate.
