What is the correct name for the ionic compound with the formula CuS?

• A. Copper(II) sulfate
• B. Copper(II) sulfide
• C. Copper(I) sulfide
• D. Copper(I) sulfate

Answer: (B)

Verified step by step guidance

1. Identify the ions present in the compound CuS. Cu represents copper, and S represents sulfur.
2. Determine the charge on the sulfur ion. Sulfur typically forms sulfide ions with a charge of 2-, written as S^{2-}.
3. Since the compound is neutral overall, the copper ion must balance the 2- charge from sulfur. This means copper has a charge of 2+, written as Cu^{2+}.
4. Name the copper ion using its oxidation state in Roman numerals. Because copper is 2+, it is named Copper(II).
5. Combine the names of the cation and anion. The anion sulfide comes from sulfur with a 2- charge, so the correct name is Copper(II) sulfide.