The attractive force that exists between the positive components (protons) and the negative components (electrons) of atoms and molecules of a substance (solid, liquid, gaseous) is termed as intermolecular force. Various physical and chemical properties of a substance depend on this force. The boiling point of a substance is higher when it has strong intermolecular forces. By comparing the boiling point of different substances we can compare the intermolecular forces of substances because the heat absorbed in boiling point is used to break these intermolecular forces of substance and to convert the liquid into vapour.
The intermolecular forces depend on the following interactions:
The strength of this interaction depends on:
3. Ion induced dipole interactions: In this a non polar molecule is polarized by an ion placed near it. The non-polar molecules get charged and behave as an induced dipole. This interaction between an ion and an induced dipole is known as ion induced dipole interaction.
4. Dipole induced dipole interaction:It is similar to that of ion induced dipole interaction. But in this a non-polar molecule are induced due to the presence of a polar molecule nearby.
5. Dispersion forces or London forces: It operates for a short distance and it is the weakest force. This kind of force arises due to movement of electrons thus creating temporary positive and negative charged regions.