Which set of compounds is arranged in order of increasing magnitude of lattice energy?

• A. NaI < NaBr < NaCl
• B. NaCl < NaBr < NaI
• C. NaI < NaCl < NaBr
• D. NaBr < NaI < NaCl

Answer: (A)

Verified step by step guidance

1. Recall that lattice energy is the energy released when one mole of an ionic crystalline compound forms from its gaseous ions. It depends mainly on the charges of the ions and the distance between them (ionic radii).
2. Understand that lattice energy increases with higher charges on the ions and decreases with larger ionic radii because the electrostatic attraction becomes weaker as ions get farther apart.
3. Since all compounds given (NaI, NaBr, NaCl) have the same charges on their ions (Na⁺ and halide ions with charge -1), the difference in lattice energy is primarily due to the size of the halide ions: I⁻ > Br⁻ > Cl⁻ in size.
4. Recognize that smaller ions lead to stronger attractions and thus higher lattice energies. Therefore, NaCl, with the smallest anion (Cl⁻), will have the highest lattice energy, and NaI, with the largest anion (I⁻), will have the lowest.
5. Arrange the compounds in order of increasing lattice energy based on ionic size: NaI < NaBr < NaCl.