Question

Why does the lattice energy increase as the size of an ion decreases?

Answer 1

• The lattice energy of an ionic solid is defined as the energy required to completely separate one mole of a solid into its gaseous constituent ions.
• If the size of a cation is smaller for an anion or the size of an anion is smaller for a cation, the distance between the ions i.e., the internuclear distance will be smaller.
• Hence, the force of attraction between them will be stronger.
• Additional energy will be required to separate these ions.
• Hence, lattice energy increases as the size of an ion decreases.