Why are ionic compounds good conductors of electricity when they are in a liquid state but not solid?
Ionic compounds, like NaCl or MgSO4, form crystal lattices in a solid state. Thus, there are no moving bits. The +ves and the -ves are bound firmly to each other. There are no delocalised electrons, as in metals or some covalent structures, so they can’t migrate either. In a liquid state, the ions have enough energy to move around, which means that they are able to transfer charge by transferring themselves. So a molten salt will conduct, while a solid one won’t. Also, in an aqueous state, salts make water highly conductive because, again, the charged ions are able to move around. To show this, get distilled water and test its resistance. Now add a pinch of salt and dissolve it. Test its resistance. Booya!
