Overview
This lecture explains how ionic compounds form giant ionic lattices, their high melting and boiling points, and their electrical conductivity properties.
Formation of Ionic Compounds
- Ionic bonding occurs when a metal reacts with a non-metal, transferring electrons from metal to non-metal.
- The metal becomes a positive ion (cation), and the non-metal becomes a negative ion (anion).
- Both resulting ions achieve a stable, full outer electron shell similar to noble gases.
- Example: Sodium reacts with chlorine to form sodium chloride (NaCl).
Giant Ionic Lattice Structure
- Ionic compounds form giant three-dimensional structures called giant ionic lattices.
- In a giant ionic lattice, every positive ion is surrounded by negative ions and vice versa.
- Strong electrostatic (ionic) forces of attraction hold ions in place, and these forces act in all directions.
- These strong forces are referred to as ionic bonds.
Properties of Ionic Compounds
- Ionic compounds have high melting and boiling points due to strong electrostatic forces requiring a lot of heat energy to break.
- Example: Sodium chloride has a melting point around 800°C.
- Ionic compounds do not conduct electricity in the solid state because ions are locked in place and cannot move.
- When molten or dissolved in water, ions are free to move and carry electrical charge, allowing the compound to conduct electricity.
- In ionic conduction, it is the movement of ions (not electrons) that carries the charge.
Key Terms & Definitions
- Ionic Bond — Electrostatic force of attraction between oppositely charged ions.
- Giant Ionic Lattice — A large, regular, three-dimensional arrangement of ions in an ionic compound.
- Cation — A positively charged ion.
- Anion — A negatively charged ion.
Action Items / Next Steps
- Review and practice questions on ionic compounds and their properties from the revision workbook.