* P: Represents the element Phosphorus.

* Cl: Represents the element Chlorine.

* 2: Indicates there are two phosphorus atoms in the molecule.

* 5: Indicates there are five chlorine atoms in the molecule.

* (III): The Roman numeral "III" indicates that the phosphorus atom has a +3 oxidation state.

This compound is also sometimes referred to as Diphosphorus Pentachloride, although the systematic name, Phosphorus(III) Pentachloride, is more widely accepted.