Oxidation and Reduction in Terms of Electrons

Key Objectives

• Explain oxidation and reduction in terms of electrons.
• Identify oxidation and reduction in half-equations or in simple equations.

Definitions

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

Example 1: Magnesium Atom

• Equation: Mg -> Mg^2+ + 2e-
  • Magnesium atom is oxidized as it loses electrons.
• This type of equation is called a half-equation.

Example 2: Sulfur Atom

• Equation: S + 2e- -> S^2-
  • Sulfur atom is reduced as it gains electrons.

Mnemonic to Remember

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

Practice Examples

1. Aluminum Atom
   • Equation: Al -> Al^3+ + 3e-
   • Aluminum atom has lost electrons: Oxidation reaction.
2. Oxygen Atom
   • Equation: O + 2e- -> O^2-
   • Oxygen atom has gained electrons: Reduction reaction.

Identifying Reactions in Symbol Equations

• Question: Identify which element has been oxidized and which has been reduced in the reaction below.
  • Equation: Zn + CuSO4 -> ZnSO4 + Cu
  • This is a displacement reaction.
  • Zinc: Zn -> Zn^2+ + 2e-
    • Zinc atom has lost electrons: Oxidized.
  • Copper: Cu^2+ + 2e- -> Cu
    • Copper ion has gained electrons: Reduced.

Additional Resources

• More questions can be found in the revision workbook available through the provided link.