6.1.4—And use the terms oxidising agent and reducing

An oxidising agent causes another species to lose electrons and is reduced itself. A reducing agent causes another species to gain electrons and is oxidised itself.

Write the electron change for the agent, not just the reaction partner. Stronger agents are better electron acceptors or donors under the stated conditions.

In Cl₂ + 2Br⁻ → 2Cl⁻ + Br₂, chlorine accepts electrons and is the oxidising agent; bromide donates electrons and is the reducing agent.

The agent’s name describes what it does to the other species, not the change it undergoes. The oxidising agent does not undergo oxidation.