In the ion dissociation process, when ions separate, all the ions separate

Explanation

\[ \text{CaCl}_2(\text{s}) \xrightarrow{\text{H}_2\text{O}}\text{Ca}^{2+}\text{(aq) } + \text{2Cl}^-\text{(aq)} \]When CaCl₂ dissolves, the one Ca²⁺ ion and the two Cl^- ions separate from each other.  That is, the two chloride ions go off on their own.  They do not remain as Cl₂ (that would be elemental chlorine; these are chloride ions); they do not stick together to make \( \text{Cl}^-_2 \) or  \( \text{Cl}^{2-}_2 \).  They become dissociated ions in their own right.  Polyatomic ions also retain their overall identity when they are dissolved.