The intermolecular forces (F) of attraction can be described as given:
1) Cohesion. The force of attraction among molecules of the same substance is known as the force of cohesion. The tension of cohesion is maximumized in solids, lesser in liquids and least in gases. It is for this reason that the solids have exact shape and resist all deforming forces.
Illustration: The solids exhibit their rigid character and exact shape due to strong force of cohesion among their molecules.
2) Adhesion: The force of attraction among the molecules of the different substances is known as the force of adhesion.
Illustration: (i) A piece of paper sticks to another due to large force of adhesion among the paper and the gum molecules.
(ii) Paint sticks to wood (and other surfaces) because of large force of adhesion among the surface of wood and paint.