# Why does the compound magnesium oxide has a high melting point?

Why? Because $M g O$ is a non-molecular solid.....held together by strong electrostatic bonds........
$M g O$ is a non-molecular, ionic solid. The material consists of an infinite array of magnesium and oxide ions that are held together by strong electrostatic bonds that persist thruout the entire lattice.
As chemists, as physical scientists, we should look at some data. The melting point of $M g O$ is $2852$ ""^@C. That of $M g C {l}_{2}$ is $714$ ""^@C. Clearly, the double charge of each constituent ion in $M g O$ strengthens the electrostatic interaction.