The passage of electric current in conductors is due to the movement of free electrons. Also the conducting material does not undergo any chemical change. A current of electricity is a stream of electrons. Examples; Metals like Cu, Al etc. Non-metals like graphite.
The flow of current in conductors is due to the movement of ions towards oppositely charged electrodes. Such conductors result in chemical changes at the electrodes. For Examples: Solutions of acids and bases, fused salts, aqueous solutions of salts such as NaCI.
Electricity flows through a conductor due to transfer of electrons from a point of higher negative potential to one of lower potential. However, the mechanism by which this transfer takes place is different for all conductors. In order to understand the mechanism by which an electric current passes through a solution, consider the example of electrolytic cell as shown in Fig.4.1. The net result is the transfer of electrons from the cathodes side of the circuit to the anode side.