Understanding Roman Numerals in Chemical Names
The Roman numerals in parentheses after the metal name (like copper(I) and copper(II)) indicate the metal's oxidation state (its charge in the compound).
* Copper(I) means copper has a +1 charge (Cu⁺).
* Copper(II) means copper has a +2 charge (Cu²⁺).
Chloride Ion
Chloride is a nonmetal ion with a -1 charge (Cl⁻).
Forming Neutral Compounds
To form a neutral compound, the charges of the ions must balance out.
* Copper(I) chloride: Since copper(I) has a +1 charge, we need one chloride ion (with a -1 charge) to balance it out. The formula is CuCl.
* Copper(II) chloride: Since copper(II) has a +2 charge, we need two chloride ions (each with a -1 charge) to balance it out. The formula is CuCl₂.
