Question

Which of the following ions will have the highest lattice energy?

• A. \( \text{NaCl} \)
• B. \( \text{MgO} \)
• C. \( \text{KCl} \)
• D. \( \text{LiF} \)

Hint:

Remember: Lattice energy increases with higher charges and smaller ionic radii.

Answer 1

The Correct Option is B

Step 1: Recall the concept of lattice energy
Lattice energy is the energy released when one mole of an ionic compound is formed from its ions in the gas phase. The lattice energy is higher when the ions are smaller and have a higher charge.
Step 2: Compare the ionic compounds
- \( \text{NaCl} \) has Na\( ^+ \) and Cl\( ^- \), both with a charge of \( 1 \). - \( \text{MgO} \) has \( \text{Mg}^{2+} \) and \( \text{O}^{2-} \), both with a charge of \( 2 \). - \( \text{KCl} \) has K\( ^+ \) and Cl\( ^- \), with K\( ^+ \) being larger than Na\( ^+ \). - \( \text{LiF} \) has \( \text{Li}^{+} \) and F\( ^- \), with smaller ions than NaCl, but the charges are still \( 1 \).
Step 3: Conclude the highest lattice energy
Among these, \( \text{MgO} \) has ions with the highest charges (2+ and 2-) and smaller ionic radii compared to \( \text{NaCl} \), \( \text{KCl} \), and \( \text{LiF} \). Hence, it will have the highest lattice energy.
Answer:
Therefore, \( \text{MgO} \) will have the highest lattice energy. So, the correct answer is option (2).