- All material is made from small moving particles called atoms.
- Materials can be solid, liquid or gaseous, depending upon the arrangement and freedom of movement of these particles.
- Diffusion is the movement of particles from a place of high concentration to a place of lower concentration on its own accord.
- The kinetic molecular theory provides an explanation for the crystalline structure of many solids, for the tendency of solids, whether crystalline or amorphous to hold their shape and for diffusion in solids.
- Forces between molecules and atoms are largely electrical in nature. When they are brought closer than the equilibrium distance, repulsion occurs. When they are separated slightly, there is attraction. These forces account for adhesion and cohesion and for such properties of solids as elasticity, hardness, and tensile strength.
- According to kinetic molecular theory - all matter is composed of tiny particles called molecules. Molecules are always in motion. When molecules interact, they rebound elastically and without energy loss.
Words to Remember :
Brownian motion; Diffusion; Kinetic theory of matter; Plasma; Viscosity; Melting point; Boiling point.
