Oxidation and reduction—often called redox reactions—are central to understanding chemical change in IB Chemistry. These processes occur in organic chemistry, energetics, electrochemistry, and everyday reactions such as rusting and combustion. Redox concepts appear repeatedly across Paper 1, Paper 2, and practical work, so mastering them early will make later topics much easier.
If you’re still exploring how chemistry fits into the wider IB science options, you might find the comparison in Which science should I take in IB? Biology vs Chemistry vs Physics useful for seeing how analytical skills differ across subjects.
Quick Start Checklist
Before diving deeper, ensure you understand these essentials:
- Oxidation is the loss of electrons.
- Reduction is the gain of electrons.
- OIL RIG helps: Oxidation Is Loss, Reduction Is Gain.
- Oxidizing agents cause oxidation by accepting electrons.
- Reducing agents cause reduction by donating electrons.
Understanding these basics will make redox equations, half-equations, and electrochemical cells far more intuitive. If you need support in structuring your thinking or designing an IA around redox behavior, you may want to explore Navigating the IB Chemistry IA.
Oxidation: The Loss of Electrons
Oxidation is defined as the loss of electrons from a species. When an atom or ion loses electrons, its oxidation state increases. This definition is consistent across organic, inorganic, and electrochemical contexts.
Examples of oxidation include:
- Fe²⁺ → Fe³⁺ + e⁻
- 2Cl⁻ → Cl₂ + 2e⁻
Oxidation is not only about oxygen. Early definitions tied oxidation to gaining oxygen or losing hydrogen, but the electron-transfer definition is the clearest and most universal for IB Chemistry.
