Ionic compounds conduct electricity when they are dissociated into positive and negative ions that are free to move. The larger the number of mobile positive and negative ions, the more conductive the ionic material becomes.
Ionic dissociation may result when the compound is dissolved in polar solvents such as water. Many ionic compounds dissociate in polar solvents to give their respective positive and negative ions. An example is sodium chloride, which dissociates into positive sodium ions and negative chlorine ions. When positive and negative electrodes are dipped in the solution, positive ions are attracted towards the negative electrode, while negative ions are attracted towards the positive electrode. The conductivity of the solution is determined by the number of conducting species and the mobility of these species in the solution. Factors affecting these two criteria include the solubility constant and solution temperature. Increasing temperature often increases the solubility of a partially dissociating ionic solid in a solution, leading to higher conductivity. Higher temperature also imparts the ionic species with higher thermal kinetic energy, which also affects conductivity.
Ionic solids may also dissociate into their respective positive and negative ions when there are fused. Molten salts of ionic compounds are commonly used to extract the respective metals and nonmetals of the ionic compound through electrolysis.