Which set of compounds in the following pair of ionic compounds has the higher lattice energy? (i) K — Chemical Bonding Chemistry Question

💡 Solution & Explanation

Step 1: Lattice energy is directly proportional to the product of charges on the ions (q1 * q2) and inversely proportional to the distance between them (r_c + r_a). Charge is the dominant factor. Step 2: Compare each pair: (i) MgO (+2, -2) has a much higher lattice energy than KCl (+1, -1); (ii) LiF and LiBr have the same charges, but F^- is smaller than Br^-, so LiF has higher lattice energy; (iii) Mg3N2 has higher charges (Mg^2+ and N^3-) and smaller sizes than NaCl (Na^+ and Cl^-), so Mg3N2 has much higher lattice energy. Step 3: Therefore, the set of compounds with higher lattice energy is MgO, LiF, and Mg3N2, matching option (d).