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6 CHEMICAL BONDING eLearn.Punjab

6.6 THE EFFECT OF BONDING ON THE PROPERTIES OF
COMPOUNDS

The properties of substances are characterized by the types of bonding present in them.
Here, we shall consider the effects of the type of bond on physical and chemical properties of
compounds.

(1) Solubility

(a ) Solubility of Ionic Compounds

Mostly, ionic compounds are soluble in water but insoluble in non-aqueous solvents. When
a crystal of an ionic substance is placed in water, the polar water molecules detach the cations
and anions from the crystal lattice by their electrostatic attraction. Thus, the ions are freed from
the crystal lattice by hydration. This happens when the hydration energy is greater than the lattice
energy and the ions are freed from their positions in the crystal. Many ionic compounds do not
dissolve in water, as the attraction of water molecules cannot overcome the attraction between
the ions. For the same reason, non-polar solvents like benzene and hexane do not dissolve, ionic
compounds.

(b) Solubility of Covalent Compounds

In general, covalent compounds dissolve easily in non-polar organic solvent (benzene, ether, etc.)

Here, the attractive forces of solvent molecules are enough for overcoming the intermolecular
forces of attraction. Mostly, covalent compounds are insoluble in water. However, some of them
dissolve in water due to hydrogen bonding.

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