The characteristics of the particles of matter are:

(1) Particles of matter have space between them:

All matter consists of particles which have space between them. Hence when two different substances are mixed, the particles of one substance get into the spaces between particles of the other. The intermixing of particles of two different types of matter on their own is called diffusion.

(2) Particles of matter attract each other:

The particles of matter are held together by forces of attraction. These inter-molecular forces of attraction are responsible for the physical and chemical nature of the substance.

The strength of the force of attraction between particles of matter increase in the order:

Gases<Liquids<Solids