Comparing the two relative forces of electrostatic attraction that you calculated, you can conclude that ionic bonding is considerably stronger in magnesium oxide.
Metallic Bond A metallic bond is a chemical bond, in which the atoms do not share or exchange electrons to bond together.
However, the action of the anion's accepting the cation's valence electrons and the subsequent attraction of the ions to each other releases lattice energy and, thus, lowers the overall energy of the system.