How do ferric ions and ferrous ions differ in charge and oxidation state?

Ferric and ferrous ions are two forms of iron that differ in their oxidation state and electrical charge.

• Ferric ion: This refers to the iron ion with a +3 oxidation state, written as ${\text{Fe}}^{3+}$. In systematic nomenclature, it is known as the iron(III) ion.123
• Ferrous ion: This refers to the iron ion with a +2 oxidation state, written as ${\text{Fe}}^{2+}$. In systematic nomenclature, it is known as the iron(II) ion.23

The use of the terms "ferric" and "ferrous" is an older naming convention where the suffix -ic denotes the ion with the higher charge, while the suffix -ous denotes the ion with the lower charge. In modern inorganic chemistry, these ions are more precisely identified by their oxidation numbers using Roman numerals in parentheses, such as iron(III) and iron(II).31