Matter in Our Surroundings Class 9 Notes Science - Chapter 1

Chapter: 1

What Are Matter In Our Sourroundings?


Anything that ocvcupies space and has mass is called Matter.

Physical Nature Of Matter

• Matter is made up of particles.

• The particles of matter are very small they are small beyond our imagination.

Characteristics Of Particles Of Matter

• Particles of matter have space between them.

• Particles of matter are continuously moving.

• Particles of matter attract each other.

States Of Matter

• There are three states of matter namely solid, liquid and gas.

• The main difference between these states of matter are given below:


States Of Matter


  • • Definite shape
  • • Distinct boundaries and fixed volume
  • • Not compressible
  • • Cannot flow
  • • Very less inter-particle space
  • • Maximum density
  • • Negligible rate of diffusion
  • • Inter-particle attraction is maximum


  • • No definite shape
  • • Fixed volume
  • • Can be compressible
  • • Can flow
  • • Inter-particle spaces are more than in solids
  • • Density is between that of the solids and gases
  • • Rate of diffusion depends on inter-particle attraction
  • • Inter-particle attraction is medium


  • • No definite shape
  • • No fixed volume
  • • Highly compressible
  • • Can flow
  • • Large inter-particle space is available
  • • Minimum density
  • • Maximum rate of diffusion
  • • Inter-particle attraction is minimum

Effect Of Temperature

• The temperature at which a solid melts to become a liquid at the atmospheric pressure is called its melting point.

• The temperature at which a liquid starts boiling at the atmospheric pressure is known as its boiling point.
Boiling is a bulk phenomenon.

• The phase change phenomenon where the substance is transformed form liquid state to solid state is known  as freezing point.

• The phenomenon of changing of a liquid into its vapour state at any temperature below its boiling point is called evaporation. Evaporation is a surface phenomenon.

Factors affecting Evaporation

1. An increase in surface area increases evaporation.

2. An increase in temperature increases the rate of evaporation.

3. A decrease in humidity increases the rate of evaporation.

4. An increase in wind speed increases the rate of evaporation.

5. Evaporation causes cooling effect.

• The change of the state of matter from the gas phase into liquid is known as condensation, it is reverse of evaporation.

• A change of state directly from solid to gas without changing into liquid state (or vice versa) is called sublimation.

• The phase change from the gaseous state to a solid state, without passing through the liquid state, is called deposition or re-sublimation.

Some Measurable Quantities and there Units

Quantity Unit Symbol
Temperature Kelvin K
Length Metre m
Mass Kilogram Kg
Weight Newton N
Volume Cubic metre m3
Density Kilogram per cubic metre Kg/m3
Pressure Pascal Pa