Balancing Redox Reactions: The 5-Step Ion-Electron Method
By Periodic Learn Editorial Team · Published September 10, 2026 · Updated October 15, 2026 · 7 min read
The ion-electron method balances redox reactions reliably because it tracks charge as carefully as it tracks atoms. Follow the same five steps every time and the coefficients fall out by themselves.
Step 1: Assign oxidation states
Work out the oxidation state of each atom to identify what is oxidised (increase) and what is reduced (decrease). This also tells you the two half-reactions you will build.
Step 2: Split into half-reactions
Write the oxidation half-reaction and the reduction half-reaction separately, keeping only the species that change oxidation state plus the atoms needed to balance them.
Step 3: Balance atoms, then oxygen
Balance every element except hydrogen and oxygen. In acidic medium, balance oxygen by adding water molecules to the oxygen-poor side.
Step 4: Balance hydrogen and charge
Balance hydrogen by adding H+ ions, then balance the net charge by adding electrons to the more positive side. In basic medium, add OH- to both sides and combine H+ and OH- into water.
Step 5: Combine and simplify
Multiply each half-reaction so the electrons cancel, add them, and cancel species that appear on both sides. Check that both atoms and charge balance in the final equation.
The single most common error is balancing atoms but forgetting charge. Always do a final charge audit on both sides.