Anything that has mass and occupies space (i.e., has volume) is called matter. Everything in the universe is made up of matter. The air breath, the food we eat.

Characteristics of Particles of matterParticles of matter have space between themParticles of matter attract each otherParticles of matter are continuously moving

STATES OF MATTER Solid- particles are closely spaced. Cohesive force is very strong. Liquid- particle is packed loosely. Cohesive force is strong. Gas- particle is far away. No cohesive force exist.

PROPERTIES OF SOLIDS • It has a definite shape and volume • It is rigid and incompressible • It has a high density • It does not flow • It is characterized by high melting and boiling points

PROPERTIES OF LIQUIDS • It has no definite shape but has a definite volume • It has slight compressibility • It has a lower density • It diffuses more readily • The boiling point is lower than solid

PROPERTIES OF GASES • It does not have a definite shape and volume • It has high compressibility • It has very low densities • It has a high rate of diffusion • It flows freely

CHANGE OF STATE OF MATTER Matter can change its state by • Changing temperature • Changing pressure • Changing temperature and pressure both

Effect of change of temperature During melting, the temperature does not rise as the latent heat of fusion is used up to overcome the forces of attraction between ice particles.

During boiling, the temperature does not rise as the latent heat of vaporization is used up to over the forces of attraction between water particles.

At 0° C, energy of water particles is much more than the ice particles. At 100° C, energy of water vapors is much more than the energy of water.

Sublimation: The change of solid directly into vapors on heating and of vapors into solid on cooling without passing through the intervening liquid state.

Effect of Change of Pressure: By applying high pressure, the gas particles can be brought close together. Thus, states of matter are determined by temperature & pressure.

Evaporation A surface phenomenon in which liquid changes into vapors at any temperature below its boiling point. Particles on surface have higher kinetic energy, so they break.

Factors affecting evaporation: • Surface area • Temperature • Humidity • Wind Evaporation cause cooling:  When liquid evaporates, it takes latent heat from surrounding which on losing heat get cool.