Question

Explain why:
(a) Covalent compounds have generally low melting points.
(b) Ionic compounds have generally high melting points.

Answer 1

(a) Covalent compounds have generally low melting points because
Simple molecular substances consist of molecules in which the atoms are joined by strong covalent bonds. However, the molecules are held together by weak forces so these substances have low melting and boiling points. They do not conduct electricity.

(b) These oppositely charged compounds are held together by strong electrostatic forces of attraction. As these forces are very strong, a considerable amount of heat energy is required to break them. Hence, the ionic compound has a high melting point.