Final answer:
Corrosion of the negative electrode occurs through oxidation, where metal atoms lose electrons and become ions. The presence of a cathode facilitates the process by acting as the site for reduction in the electrochemical reaction. The electrons generated by the oxidation at the negative electrode flow through the external circuit, completing the electrochemical cell.
Step-by-step explanation:
Corrosion of the negative electrode occurs due to a process called oxidation. When a metal is exposed to oxygen, it can undergo a chemical reaction known as oxidation, where the metal atoms lose electrons and become ions. In the case of the negative electrode, the metal atoms are oxidized to ions, causing the electrode to be eaten away. This process is facilitated by the presence of a cathode, which acts as the site for reduction in an electrochemical reaction. The electrons generated by the oxidation at the negative electrode are transported through the external circuit, completing the electrochemical cell.