How many iron and chlorine atoms are in iron(III) chloride (FeCl3)?

In one molecule of iron(III) chloride (FeCl₃), there is 1 iron atom and 3 chlorine atoms.

Explanation:

The chemical formula FeCl₃ tells us the ratio of iron (Fe) and chlorine (Cl) atoms in the compound. The subscript numbers indicate the quantity of each atom. Since there is no subscript after Fe, it is understood to be 1. The subscript 3 after Cl indicates that there are 3 chlorine atoms.