Ionic compounds have the ability to conduct electricity when in a molten state because their ions are free to move and carry electrical charge.

In their solid form, ionic compounds consist of a lattice structure in which ions are held together by strong electrostatic forces of attraction. This rigid arrangement restricts the movement of the ions, preventing them from conducting electricity. However, when an ionic compound is melted or dissolved in water, the lattice structure is disrupted. The heat energy supplied during the melting process is sufficient to overcome the strong forces of attraction between the ions, allowing them to move freely and independently.

These mobile ions are charged particles. When an electric current is applied, the positive ions, known as cations, migrate towards the negative electrode (the cathode), while the negative ions, or anions, move towards the positive electrode (the anode). This movement of ions constitutes an electric current, explaining why molten ionic compounds can conduct electricity.

It is important to note that not all ionic compounds will conduct electricity when molten. The conductivity depends on the presence of mobile, charged particles. Therefore, if an ionic compound does not dissociate into ions when melted, it will not be able to conduct electricity.

In summary, the ability of molten ionic compounds to conduct electricity arises from the presence and movement of free ions, which carry the electrical charge. This principle is fundamental to the field of electrochemistry, which explores the relationship between electricity and chemical reactions.