electrons leave this compartment travel through the external circuit and enter the cathode compartment their reduction takes place at a copper electrode dipping into a copper nitrate solution a salt bridge maintains change neutrality in the two compartment let's zoom into the atomic scale and see how this cell operates here at the anode. the site of oxidation zinc Adams in the metal bar are in contact with the surrounding electrolyte solution. each atom loses to electrons and becomes zinc ion which diffures into the solution the electrons given up enter the bar enjoin the flow of electrons up to ward the external circuit.