Oxidation and Reduction in Terms of Electrons

Key Concepts

Definitions

• Oxidation: Loss of electrons.
• Reduction: Gain of electrons.

Acronym to Remember

• OIL RIG: Oxidation Is Loss (of electrons), Reduction Is Gain (of electrons)

Displacement Reactions Recap

• More reactive element displaces a less reactive element from its compound.
• Example: Magnesium (Mg) displaces Iron (Fe) from Iron Oxide (Fe₂O₃)
  • Mg is oxidized (gains oxygen)
  • Fe is reduced (loses oxygen)

Half Equations

• Show electron transfer processes in reactions.
• Example 1: Mg → Mg²⁺ + 2e⁻
  • Mg is oxidized (loses electrons)
• Example 2: S + 2e⁻ → S²⁻
  • S is reduced (gains electrons)

Practice Problems

1. Aluminium Half Equation: Al → Al³⁺ + 3e⁻
   • Al is oxidized (loses electrons)
2. Oxygen Half Equation: O + 2e⁻ → O²⁻
   • O is reduced (gains electrons)

Identifying Oxidation and Reduction in Symbol Equations

• Example: Zn + CuSO₄ → ZnSO₄ + Cu
  • Zinc (Zn) starts as atom, ends as ion (Zn²⁺): Oxidized
  • Copper (Cu) starts as ion (Cu²⁺), ends as atom: Reduced

Further Study

• Refer to the revision workbook for additional questions and practice on oxidation and reduction.