In the naming of ionic compounds, what do the Roman numerals in a cation's name indicate?

• A. The charge of the cation
• B. The number of atoms in the compound
• C. The number of electrons in the cation
• D. The total number of ions in the formula unit

Answer: (A)

Verified step by step guidance

1. Understand that ionic compounds consist of cations (positively charged ions) and anions (negatively charged ions).
2. Recognize that some elements, especially transition metals, can form cations with different possible charges.
3. The Roman numerals in the name of a cation indicate the specific charge (oxidation state) of that cation in the compound.
4. This helps distinguish between different ionic compounds formed by the same element but with different charges, for example, Fe(II) vs Fe(III).
5. Therefore, the Roman numeral tells you the charge of the cation, not the number of atoms, electrons, or total ions.