Grade 10 Science
posted by Alisha on .
Why is the name for the ionic bond FeS Iron (II) Sulphide when the charges on iron and sulphur are +2 and -2? Shouldn't the name be Iron (I) Sulphide?
Same goes for Copper (II) Sulphide.
Iron can exist as either a divalent or trivalent cation. There's the Fe2+ and Fe3+ cations. The (II) refers to the valency of the Iron cation. Since it's the 2+ cation, then it's called Iron (II) Sulphide. If it was the Iron 3+ cation, for example in Iron oxide (rust) aka Fe2O3, it's called Iron (III) oxide.
Same with Copper. It exists in more than one valency. There's Copper (I) oxide (Cu2O) and Copper (II) oxide (CuO).