Question

Covalent compounds generally have low melting and boiling points.
(A) True
(B) False

Answer 1

Hint: Solve this question by discussing the property of covalent compounds and the nature of intermolecular forces acting between them. Covalent compounds are those which are formed by equal sharing of electrons.

Complete step by step answer:
> There are three kinds of interatomic bonds, namely, ionic, covalent and coordinate.
> Covalent bond is the kind of bond formed by equal sharing of electrons. The shared electrons are called ‘bonding pairs of electrons. Covalent bonds are very stable and the interatomic forces are quite strong. But, the intermolecular forces between covalent compounds are weak. Covalent compounds are held together by weak intermolecular forces. It is because of such weaker forces, which fails to make the compound bind tightly.
Since the forces are weak, it needs only a little amount of energy to break. Heat is a form of energy. Since lower heat (energy) is capable of breaking these weak intermolecular forces, therefore the melting and boiling points of covalent compounds is low.

Additional Information: Ionic compounds are very strongly bonded due to electrostatic forces between them. Hence, they have higher boiling and melting points.

Note: All covalent compounds have some sort of ionic character in it. Covalent bonds are not hundred percent covalent in nature. This exists due to the difference in electronegativity amongst the elements. The more electronegative element tends to pull the electron pair towards it and hence develops a delta negative charge, making the other element a delta positive charge.