Why are ionic compounds non-conductors of electricity when they are solid, but good conductors when?
To say that Ionic compound are not conductors of electricity is not absolute. There are some ionic compounds which do. They are called, “fast ion conductors” and an example is YSZ (Yttria-stabilized zirconia) But since you are asking about the general rule here you go: The reason the vast majority of ionic compounds do not conduct electricity when they are solid is because of the nature of the ionic compounds structure. Take table salt for example, NaCl. Because it is an Ionic compound it forms a crystalline structure, stacking on top of each other, to the right and left and so forth. The Na molecules have no where to go and the Cl molecules are in the same boat. This lack of movement creates the inability to carry a charge, but when they are molten this structure is no longer present and the molecules are able to move around and interact with the electrodes thus they can carrying the charge. To the exception YSZ, the reason this ionic compound can conduct electricity is because of its
