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How is FeCl3 named using the charge of its iron ion?

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Two diagrams show the three-dimensional structure of a methane molecule: panel A uses a ball-and-stick model with a central carbon atom connected to four hydrogen atoms in a tetrahedral arrangement, while panel B illustrates the bond angle of 109.5 degrees and bond length of 1.09 angstroms between carbon and hydrogen atoms. — chemical compound Methane, in which four hydrogen atoms are bound to a single carbon atom, is an example of a basic chemical compound. The structures of chemical compounds are influenced by complex factors, such as bond angles and bond length.

Because iron can form more than one type of cation, the nomenclature for its binary ionic compounds must specify the charge of the metal ion present.

In the compound ${FeCl}_{3}$ , the iron exists as an ${Fe}^{3 +}$ ion. According to systematic naming rules, this is designated as iron(III) chloride, where the Roman numeral (III) explicitly indicates the $+ 3$ charge of the iron ion.1

Alternatively, an older naming system uses suffixes to distinguish between the two common oxidation states of iron. In this system, the ion with the higher charge ( $+ 3$ ) is given the suffix -ic, while the ion with the lower charge ( $+ 2$ ) receives the suffix -ous. Consequently, ${FeCl}_{3}$ is also commonly referred to as ferric chloride, whereas ${FeCl}_{2}$ is known as ferrous chloride.12