EVERYDAY SCIENCE

Detailed explanation-1: -The molecules of covalent compounds are held by weak intramolecular forces. Thus, a very small amount of energy is required to break the bonds between two or more molecules. That is why they have low melting and boiling points.

Detailed explanation-2: -This is because the atoms within the covalent molecules are very tightly held together. Each molecule is indeed quite separate and the force of attraction between the individual molecules in a covalent compound tends to be weak.

Detailed explanation-3: -Ionic bonds have very high melting and boiling points, while non‐polar covalent bonds have very low melting and boiling points. The melting and boiling points of polar covalent bonds are in between ionic and non‐polar covalent.

Detailed explanation-4: -However, although the covalent bonds holding the atoms together in a simple molecule are strong, the intermolecular forces between simple molecules are weak.

Detailed explanation-5: -The melting and boiling points of molecular compounds are generally quite low compared to those of ionic compounds. This is because the energy required to disrupt the intermolecular forces between molecules is far less than the energy required to break the ionic bonds in a crystalline ionic compound (Figure 6.2. 1) .