Copper II: Cu+2 (Note: Cu I: Cu+1)
Therefore neutral Copper II Sulfide: CuS
The trick here is to realize that the Roman numeral used to name this ionic compound tells you the oxidation state of the metal.
In this case, you know that in copper(II) sulfide, the copper cation carries a
Sulfur is located in group 16 of the Periodic Table, which implies that it forms
As you know, ionic compounds are electrically neutral. This means that the overall positive charge of the cations must be balanced by the overall negative charge of the anions.
You can thus say that a formula unit of copper(II) sulfide will contain one copper(II) cation, which carries a
#["Cu"]^(2+) + ["S"]^(2-) => "Cu"_2"S"_2 => "CuS"#