Grade 12 · Chemistry
Oxidation-reduction
Why it matters
Oxidation numbers and identifying redox.
Advanced20m readingPrerequisite: None
What is oxidation and reduction (redox)?
Short answer
Oxidation and reduction are paired processes involving the transfer of electrons. Oxidation is the loss of electrons (its oxidation number increases); reduction is the gain of electrons (its oxidation number decreases). They always occur together in a redox reaction — the substance oxidized gives electrons to the substance reduced. A common memory aid is OIL RIG: Oxidation Is Loss, Reduction Is Gain.
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Frequently asked questions
- What does OIL RIG mean?
- Oxidation Is Loss of electrons, Reduction Is Gain of electrons — a mnemonic for the direction of electron transfer.
- What is an oxidizing agent?
- The substance that gains electrons (is reduced) and thereby causes another substance to be oxidized.