The correct systematic name for CaCl2 is calcium chloride, not calcium dichloride. The reason for this lies in the rules of chemical nomenclature, specifically the naming conventions for ionic compounds.
Ionic compounds are named based on the ions they contain. In the case of CaCl2, it consists of calcium ions (Ca2+) and chloride ions (Cl–). According to the rules of naming ionic compounds, the cation (positively charged ion) is named first, followed by the anion (negatively charged ion). The name of the cation remains unchanged, while the name of the anion is derived from the element’s name but ends with the suffix ‘-ide’.
Since calcium is a metal that forms only one type of cation (Ca2+), there is no need to specify the number of calcium ions in the compound. Similarly, the number of chloride ions is determined by the charge balance required to neutralize the calcium ions. In this case, two chloride ions are needed to balance the charge of one calcium ion, resulting in the formula CaCl2.
The use of prefixes like ‘di-‘ is typically reserved for covalent compounds, where the number of atoms of each element must be specified to indicate the molecular structure. Since CaCl2 is an ionic compound, the name ‘calcium dichloride’ would be incorrect. The correct name is simply ‘calcium chloride’.