Among the following, which one has the maximum lattice energy?

CONCEPT:

Lattice Energy

• Lattice energy is the energy released when one mole of an ionic compound forms from its gaseous ions.
• The lattice energy depends on two key factors:
  • Charge of ions: Higher charges result in stronger electrostatic attraction and higher lattice energy.
  • Size of ions: Smaller ions lead to shorter interionic distances, increasing the electrostatic force and lattice energy.
• Lattice energy decreases as the size of the anion increases because larger anions create longer interionic distances, reducing the electrostatic attraction.

EXPLANATION:

• In the given options:
  • BaF₂, BaCl₂, BaBr₂, and BaI₂ are ionic compounds of barium with halide anions (F^-, Cl^-, Br^-, I^-).
  • The cation (Ba²⁺) is the same in all compounds, so the difference in lattice energy arises from the size of the anion.
  • The sizes of the halide anions increase in the order: F^- < Cl^- < Br^- < I^-.
  • Smaller anions, like F^-, result in shorter interionic distances and stronger electrostatic attraction, leading to higher lattice energy.
• Therefore, among the given options, BaF₂ has the highest lattice energy due to the smallest anion (F^-).

Correct Answer: Option 1 (BaF₂).