Why are ionic solids insulators with respect to electrical current?

1 Answer
Mar 26, 2016

Ionic solids are an infinite array of close-packed positive and negative ions that are not free to move in the solid state.

Explanation:

In the solid state of course the ions, which would otherwise carry a current, cannot move, and are constrained in the ionic lattice. In aqueous solution, the solvated ions are free to move, and can thus carry a current. Pump in enough heat to the solid, however, and the ionic lattice can liquefy, and thus give free ions that could also carry a current. Some ionic solids are low melting, but common salt, which is the subject of many laboratory demonstrations, would require a serious blow torch to melt.