How do melting points differ for ionic compounds versus those that contain only covalent bonds? Why is this so (explain)?
Melting points for ionic compounds are high generally; for covalent compounds m.p. are much lower.
Ionic compounds are held together by oppositely charged ions. To melt these compounds one must overcome this crystal lattice energy. For covalent molecules, the atoms have relatively strong attractions for each other BUT the attractions for one molecule to the other is not strong.