Properties of Ionic Compounds - AQA GCSE Chemistry

Overview of Ionic Compounds

• Ionic compounds are made up of charged particles called ions.
• They have a giant lattice structure with strong electrostatic forces of attraction.

Formation of Ionic Compounds

• Occurs when a negative ion (gains an electron) joins with a positive ion (loses an electron).
• Form regular structures known as giant ionic lattices.

High Melting and Boiling Points

• Ionic compounds have high melting and boiling points.
• Reason: Strong electrostatic forces of attraction between oppositely charged ions.
  • Energy is required to overcome these forces during melting and boiling.
  • More energy needed results in higher melting and boiling points.
• Example compounds:
  • NaCl: Melting point - 801°C, Boiling point - 1413°C
  • MgO: Melting point - 2852°C, Boiling point - 3600°C
• Ionic bonds between ions with higher charges are stronger (e.g., Mg2+ and O2- vs Na+ and Cl-).

Conductivity of Ionic Compounds

• Ionic compounds can conduct electricity when:
  • Melted to form a liquid.
  • Dissolved in water to form an aqueous solution.
• Conductivity is due to the movement of ions, which are charged particles.
• Ionic compounds do not conduct electricity in solid form as ions are in fixed positions.

Summary

• Ionic compounds have high melting and boiling points due to strong ionic bonds.
• They can conduct electricity when in liquid or aqueous state but are insulators when solid.

Additional Resources

• BBC Sounds Podcast Series
• Study guides:
  • The three states of matter
  • Bonding and structure