# Using Roman Numerals to indicate a compound

I don't completely understand it's use. Here's an example I don't understand:

Shortly after discussing $$\ce{[CuCl4]^2-}$$, an exam paper asked a question about copper(II) chloride. I understand that copper(II) chloride could refer to $$\ce{CuCl2}$$, calling it copper(II) chloride, but couldn't it also refer to $$\ce{[CuCl4]^2-}$$? I would understand the question in reference to $$\ce{CuCl2}$$, but it got confusing when I realised it could equally be referring to $$\ce{[CuCl4]^2-}$$, especially after it just mentioned it.

• $$\ce{CuCl2}$$: copper(II) chloride;
• $$\ce{[CuCl4]^2−}$$: tetrachloridocuprate(II).
Oxidation number denoted with the Roman numerals in parentheses refers to the element it's placed after and doesn't carry any additional information besides the fact that copper exists as $$\ce{Cu^2+}$$ in both compounds.