(40) GCSE Chemistry Revision "Properties of Ionic Compounds"

Overview of Ionic Compounds

• Understanding the formation, properties, and behavior of ionic compounds.

1. Formation of Ionic Compounds

1.1 Ionic Bonding

• Occurs between a metal and a non-metal.

• Example: Reaction between sodium (metal) and chlorine (non-metal).

• Electron Transfer:

  • Sodium loses one electron, becoming a sodium ion (Na+).

  • Chlorine gains that electron, becoming a chloride ion (Cl-).

• Resulting Compound: Sodium chloride (NaCl).

• Ionic Charge:

  • Sodium ion has a +1 charge.

  • Chloride ion has a -1 charge.

• Stable Structure:

  • Both ions achieve a full outer energy level, similar to noble gases.

2. Structure of Ionic Compounds

2.1 Giant Ionic Lattices

• Formation of a giant ionic lattice.

• Definition: A giant ionic lattice is a three-dimensional structure of ions.

• Arrangement:

  • Positive ions (cations) surrounded by negative ions (anions) and vice versa.

  • Example: Sodium chloride forms a crystal lattice.

• Electrostatic Forces:

  • Strong forces of attraction (ionic bonds) between oppositely charged ions.

  • These forces act in all directions within the lattice.

3. Properties of Ionic Compounds

3.1 High Melting and Boiling Points

• Explanation of physical properties:

  • High melting and boiling points due to strong electrostatic forces.

  • Requires significant heat energy to break these forces.

  • Example: Sodium chloride melts at approximately 800°C.

3.2 Electrical Conductivity

• Behavior of ionic compounds in different states:

  • Cannot conduct electricity when solid:

    • Ions are fixed in place by strong ionic bonds, allowing only vibration.

  • Can conduct electricity when molten or dissolved in water:

    • Ions are free to move and carry electric charge.

• Important Note:

  • Electricity in ionic solutions is conducted by moving ions, not electrons.

Summary

• Ionic compounds form through electron transfer between metals and non-metals, creating ions that assemble into giant ionic lattices. Their high melting and boiling points result from strong ionic bonds, while their ability to conduct electricity depends on the state (solid vs. molten/dissolved). Understanding these concepts is crucial for exams and further studies in chemistry.