* Ionic Compounds: Calcium chloride is an ionic compound. This means it's formed by the electrostatic attraction between positively charged calcium ions (Ca²⁺) and negatively charged chloride ions (Cl⁻).

* Crystal Lattice: In its solid state, CaCl₂ forms a crystalline structure. The ions are arranged in a highly ordered, three-dimensional lattice.

* Fixed Positions: The ions are held firmly in these positions by strong electrostatic forces. They are not free to move.

For a substance to conduct electricity, it needs free charge carriers. In solids, these carriers are usually electrons. Since the ions in calcium chloride are locked in place, they cannot carry electric current.

Why CaCl₂ conducts in solution or when molten:

* Dissolving: When CaCl₂ dissolves in water, the ionic bonds break. The ions become surrounded by water molecules (hydration) and are free to move. This allows them to carry electric current.

* Melting: Similarly, when CaCl₂ melts, the ions are no longer held in a fixed lattice. They can move freely and act as charge carriers, allowing the molten salt to conduct electricity.

In summary, calcium chloride conducts electricity when its ions are free to move, either in a solution or when molten. In its solid state, the ions are locked in a crystal lattice and cannot carry electric current.