What is the correct name for CuCl?
1) copper chloride
2) chlorocopper
3) copper(I) chloride
4) chlorocopper(I)
5) copper(II) chloride
The Correct Answer and Explanation is:
The correct name for CuCl is copper(I) chloride (option 3). To understand why this is the correct answer, let’s break down the components and naming conventions involved.
Copper’s Oxidation States
Copper (Cu) can exhibit multiple oxidation states, most commonly +1 and +2. In the case of CuCl, the chlorine (Cl) atom has a -1 oxidation state because it is a halogen and typically forms anions with a charge of -1. To maintain electrical neutrality in the compound, copper must be in the +1 oxidation state. Therefore, Cu in CuCl is copper(I).
Naming Conventions
The IUPAC (International Union of Pure and Applied Chemistry) naming convention for binary ionic compounds, especially those with metals that can have multiple oxidation states, requires the oxidation state of the metal to be specified in the name. This is done by including a Roman numeral in parentheses immediately following the name of the metal. In this case, since Cu is in the +1 oxidation state, it is denoted as copper(I).
Alternative Names
While the name “copper chloride” (option 1) may seem plausible, it is too ambiguous because it does not specify the oxidation state of copper. This could refer to either CuCl (copper(I) chloride) or CuCl₂ (copper(II) chloride), where Cu is in the +2 oxidation state. “Chlorocopper” (option 2) and “chlorocopper(I)” (option 4) are less common and not standard in chemical nomenclature. Finally, “copper(II) chloride” (option 5) is incorrect because that refers specifically to CuCl₂, where copper has a +2 oxidation state.
Summary
In conclusion, the most accurate and systematic name for CuCl is copper(I) chloride, as it clearly indicates both the metal and its oxidation state, adhering to the IUPAC naming conventions.