How Electron Flow Relates to Anode and Cathode

The flow of electrons is directly tied to the fundamental definitions of anode and cathode (oxidation and reduction). The rule for electron flow is universal for all electrochemical cells.

Why Does This Happen?

1. The Anode is the site of Oxidation (AN OX). Oxidation Is Loss of electrons. A chemical substance at the anode *loses* electrons, which are then released into the external wire.
2. The Cathode is the site of Reduction (RED CAT). Reduction Is Gain of electrons. A chemical substance at the cathode *gains* electrons, taking them from the external wire.

Naturally, electrons flow from where they are released (the anode) to where they are consumed (the cathode).

Electron Flow vs. Conventional Current

It is very important not to confuse electron flow with conventional current (often labeled "I" in physics diagrams).

• Electron Flow: The actual movement of negative electrons. Flows from Anode to Cathode (negative to positive in a battery).
• Conventional Current: The historical standard, defined as the flow of positive charge. It flows opposite to the electrons. Flows from Cathode to Anode (positive to negative in a battery).

What About Inside the Cell?

Electrons do not flow through the electrolyte (the internal solution). Instead, the circuit is completed by the movement of ions:

• Anions (negative ions) move toward the Anode.
• Cations (positive ions) move toward the Cathode.