Why is magnesium oxide expected to have stronger bonding than sodium chloride?

Magnesium oxide is expected to have stronger bonding than sodium chloride primarily due to the higher charges of the ions involved in its formation. In magnesium oxide (MgO), the magnesium ion carries a charge of +2, while the oxide ion carries a charge of -2. This results in stronger electrostatic forces of attraction between the ions due to the greater magnitude of the charges.

In contrast, sodium chloride consists of sodium ions (Na⁺) and chloride ions (Cl⁻), which both carry a charge of +1 and -1, respectively. The lower charges in sodium chloride lead to weaker ionic bonding compared to magnesium oxide, where the +2 and -2 charges enhance the strength of the ionic interactions significantly.

Thus, the stronger bonding in magnesium oxide is largely a consequence of the higher charges on the ions, which lead to stronger electrostatic attractions and result in a higher lattice energy for magnesium oxide compared to sodium chloride.