In thermal conduction, heat energy flows from hotter regions to cooler regions. When atoms heat up, they vibrate faster and bump into their neighbors. These frequent collisions pass the thermal energy along the physical material.
Metals contain loose electrons that also carry heat energy very efficiently. Electrical conduction transfers electric charge instead of transferring thermal energy. An applied voltage pushes charged particles completely through a given substance.
In solid metals, free electrons drift around to carry the electric current. Chemists refer to this specific process as electronic conduction. In melted salts or liquid water solutions, ions move to carry the current.
Ions are simply atoms or molecules that hold a positive or negative charge. This physical movement of ions is called ionic or electrolytic conduction. A material’s overall conductivity depends heavily on its available charge carriers.
It also depends on exactly how freely those charge carriers can move. This rule explains why solid metals conduct electricity so incredibly well. Their outermost electrons can drift freely throughout the entire solid crystal structure.
Solid salts have tightly locked ions that cannot move around the lattice. As a direct result, solid salts cannot conduct electricity at all. Students often forget that conductivity requires particles that can physically move.