In naming ionic compounds that include transition metals, what notation is used to indicate the metal's charge?

• A. Roman numerals in parentheses
• B. Suffix -ide
• C. Prefix with the metal name
• D. No notation

Answer: (A)

Transition metals can form ions with more than one possible charge, so the name shows exactly which charge the metal has in that compound. The way this is done is by writing the charge as a Roman numeral in parentheses after the metal name. This makes the name unambiguous about the metal’s oxidation state, which is crucial for correctly determining the formula. For example, iron can exist as Fe2+ or Fe3+, so the compounds are named iron(II) chloride and iron(III) chloride to specify which ion is present. The suffix -ide is used for the anion part (like chloride or oxide) rather than indicating the metal’s charge, and prefixes (mono-, di-, etc.) are used for covalent compounds, not to denote the oxidation state of metals in ionic salts. Without the Roman numeral, you’d lose information about the metal’s charge and could misidentify the compound.