Properties of Ionic Compounds | Chemistry for Grade 11 (IGCSE) PDF Download

Properties of Ionic Compounds

• Ionic compounds are typically solid at room temperature.
• They exhibit high melting and boiling points.
• Ionic compounds demonstrate conductivity in the molten state or when dissolved in a solution.
• However, they are poor conductors in their solid state.

Explaining the Properties of Ionic Compounds

• Ionic compounds exhibit high melting and boiling points because of the strong electrostatic forces between oppositely charged ions.
• These electrostatic forces operate in all directions, necessitating a significant amount of energy to overcome them.
• The strength of the electrostatic forces and thus the melting point is directly proportional to the charge on the ions.
  • For instance, magnesium oxide (MgO) comprising Mg^2+ and O^2- ions has a higher melting point compared to sodium chloride (NaCl) containing Na^+ and Cl^- ions.
• For electric current to flow, there must be freely moving charged particles like electrons or ions present.
• Ionic compounds act as good conductors of electricity in the molten state or in solution due to the presence of mobile ions that can carry a charge.
• In contrast, they are poor conductors in the solid state since the ions are fixed in positions within the lattice and cannot move.