* Coulomb's Law: Lattice energy is directly proportional to the product of the charges of the ions and inversely proportional to the distance between them.

* Charge: MgO has a higher charge (Mg²⁺ and O²⁻) compared to NaCl (Na⁺ and Cl⁻). This means the electrostatic attraction between ions in MgO is stronger.

* Ionic Radius: Mg²⁺ and O²⁻ are smaller ions than Na⁺ and Cl⁻. This means the distance between the ions in MgO is smaller, leading to a stronger electrostatic attraction.

In summary: The combination of higher charges and smaller ionic radii in MgO results in significantly greater lattice energy compared to NaCl.