What is the correct name for the ionic compound with the formula Cu_2S?

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

Answer: (A)

Verified step by step guidance

1. Identify the ions present in the compound Cu_2S. The compound consists of copper (Cu) and sulfur (S).
2. Determine the charge on the sulfide ion. Sulfur typically forms the sulfide ion with a charge of 2-, written as S^{2-}.
3. Since the formula is Cu_2S, there are two copper atoms balancing one sulfide ion. To balance the 2- charge from sulfide, the total positive charge from copper must be +2.
4. Divide the total positive charge by the number of copper atoms to find the charge on each copper ion: +2 total charge / 2 copper atoms = +1 charge per copper ion. This means copper is in the +1 oxidation state.
5. Name the compound using the oxidation state of copper in Roman numerals: Copper(I) sulfide.