Matter in Our Surroundings Class 9 Notes Science - Chapter 1

Chapter: 1

What Are Matter In Our Surroundings?

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    Matter

    Anything that occupies 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:
    statesofmatter

    States Of Matter

    Solid Liquid Gas
    • Definite shape
    • No definite shape
    • No definite shape
    • Distinct boundaries and fixed volume
    • Fixed volume
    • No fixed volume
    • Not compressible
    • Can be compressible
    • Highly compressible
    • Cannot flow
    • Can flow
    • Can flow
    • Very less inter-particle space
    • Inter-particle spaces are more than in solids
    • Large inter-particle space is available
    • Maximum density
    • Density is between that of the solids and gases
    • Minimum density
    • Negligible rate of diffusion
    • Density is between that of the solids and gases
    • Maximum rate of diffusion
    • Inter-particle attraction is maximum
    • Rate of diffusion depends on inter-particle attraction
    • Inter-particle attraction is minimum
    • Inter-particle attraction is medium

    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