Redox Reaction: Sodium and Chlorine

Overview

• Reaction: Sodium metal and chlorine gas combine to form sodium chloride (table salt).
• Process:
  • Sodium atoms lose one electron to form sodium ions.
  • Chlorine atoms gain one electron to form chloride ions.

Key Concepts

• Half Reactions:

  • Illustrates electron transfer.

• Redox Reaction:

  • Stands for oxidation-reduction reaction.
  • Oxidation: Substance loses electrons.
  • Reduction: Substance gains electrons.

Example: Sodium and Chlorine

• Sodium (Na):
  • Oxidized: Loses electrons, becomes a sodium ion.
  • Reducing agent: Facilitates reduction of chlorine.
• Chlorine (Cl):
  • Reduced: Gains electrons, becomes chloride ion (Cl⁻).
  • Oxidizing agent: Facilitates oxidation of sodium.

Understanding Charges

• Reduction of Charge:
  • Neutral chlorine becomes chloride ion with a 1⁻ charge, reducing its charge.

Assigning Oxidation Numbers

• Oxidation Numbers:
  • Represent electrical charges, not formal charges.

Rules for Assigning Oxidation Numbers

1. Elements: Oxidation number is zero.
2. Monoatomic Ions: Oxidation number equals their formal charge.
3. Hydrogen: Typically +1, -1 in hydrides.
4. Oxygen: Typically -2, -1 in peroxides.
5. Halogens: Typically -1.
6. Sum of Oxidation Numbers:
   • Neutral molecule: Sum must be 0.
   • Polyatomic ion: Sum must equal the ion's formal charge.

Practice

• Assign Oxidation Numbers: Apply rules to compounds to ensure they sum to correct total based on molecule or ion type.