What is the chemical formula for copper(II) sulfide?

The chemical formula for copper(II) sulfide is correctly represented as CuS. Copper(II) signifies that copper has a +2 oxidation state. Sulfide indicates the sulfide ion (S²⁻), which has a -2 charge. To achieve electrical neutrality in the compound, one copper ion (Cu²⁺) combines with one sulfide ion (S²⁻), resulting in the formula CuS.

In this case, choosing CuS reflects the correct stoichiometry that balances the charges of the copper and sulfide ions, ensuring the compound is stable and neutral. This clarity in oxidation states and charges is crucial in determining the correct nomenclature and formula for ionic compounds.