When a substance melts, bonds between the particles within the solid are broken, allowing the particles to become mobile and fluid. Ionic bonds and covalent bonds between atoms are comparable in strength; in fact, if anything, covalent bonds are stronger. Yet you probably noticed a marked difference between the melting behavior of ionic and covalent compounds...one of them took much less energy to break those bonds. How can you explain this apparent contradiction? Think about what the bonds do hold together, and what they do not.