Intermolecular forces are the electrostatic force. It is defined as the different repulsive and attractive forces between the molecules which is the outcome of the polarity of the molecules present. It is observed that when two or more atoms combines together it forms a combination which is known as the molecules. The force by which two atoms held each other is known as the intermolecular force. The intermolecular force helps in determining whether the substance is solid, gaseous, and liquid. The intermolecular forces helps in determining the interaction between two molecules. The intermolecular force can also be described as the interaction between the negative and positive charges. In case of the ionic and covalent bonds it is observed that the interaction which is in between the molecules is the sum of the repulsive and attractive elements. Intermolecular force is important as it helps in holding the molecular together and reduces the distance between the molecules. In case of liquid and solid substance the intermolecular force plays a vital role.

However the intermolecular forces are of three types. They are as follows:-

Dipole- Dipole interactions
London dispersion force
Ion-dipole interaction

The dipole-dipole interaction happens when two polar molecules are attracted towards each other. The positive side of the molecule is attracted towards the negative side of another molecule. Most of the molecules present are polar, therefore the dipole-dipole interaction is one of the common type of intermolecular force. Example: The interaction between the molecules of the sulphur dioxide is a type of dipole-dipole attraction. Where the atom of sulphur of one molecule is attracted with the atom of the oxygen of the other molecule. The hydrogen bonding is one of the best example of this type of intermolecular force. In the case of the hydrogen atom one molecule of the hydrogen atom is attracted towards the electronegative atom of another hydrogen molecules.

The London dispersion force consists of the dipole force which is induced. It can be stated that the London dispersion force is one of the weakest among all the three types of intermolecular forces. This type of intermolecular force is observed among two molecules which is non-polar in nature. In such type of intermolecular forces the electrons present in one molecules is attracted with the nucleus of a different molecule. The dipole force is induced when the electron cloud gets distorted by the repulsion and attraction electrostatic forces. Example: The interactions among the two methyl groups, interactions among the molecules of the oxygen and nitrogen gases.

The ion-dipole interaction is observed when a polar molecule is encountered by an ion. In such type of intermolecular forces the charge of the ion is used to determine that which portion of the molecules will repel and attract. It is observed that the cation which are the positive ion is attracted towards the anion which is the negative charged ion. Example: The interaction between the sodium ion with the atom of the oxygen and the repulsion of the hydrogen and sodium with one another is an example of ion- dipole interaction.