Revision notes class 9th Science Ch:1

                 Ch:1Chemistry

   Matter In Our Surroundings    

ℐ𝓃𝓉𝓇ℴ𝒹𝓊𝒸𝓉𝒾ℴ𝓃

🔅 Everything in this universe      is made up of material which scientists have named "mater".The air we breadth ,the food we eat, stones, clouds, plants and animals, even a small drop of water or a particle of sand-every thing is matter.

🔅 Matter:Matter is the substance which have mass and occupies space and matter is made up of very tiny particles.

Example:Notebook, pen, star, sun, planet, air etc...

🔅 Characteristics of Particles

1) They are continuously moving

2) They having space between them

3)They attract each other

1)Particles of matter are continuously moving.

Particles posses kinetic energy.As the temperature rise particles moves faster because kinetic energy increases.

🔅Movement Is

🔅Minimum in solids.

🔅More in liquids.

🔅Maximum in gases.

2)Particles of Matter having space between them.

The space between the particles.

🔅Minimum in solids.

🔅More in liquids.

🔅Maximum in gases .

3)Particles of Matter attract each other.

The force of attraction.

🔅Maximum in solids.

🔅Intermediate in liquids.

🔅Negligible in gases.

          🔅States Of Matter   

🔅Solid

🔅Definite Shape

🔅Distinct Boundaries

🔅Rigid

🔅Incompressible

🔅Definite Volume    

🔅Liquid

🔅No definite shape 

🔅No distinct boundaries

🔅Fluidity

🔅Low compressible

🔅Definite volume     

🔅Gas

🔅No definite shape

🔅No definite boundaries

🔅Fluidity

🔅High compressible     

🔅No definite volume     

🔅Change Of State Of Matter  

By Changing Temperature     

            Solid                                              Liquid

            Gas                         

By Changing Pressure

            Gas

            Liquid

            Solid

 

🔅By Changing Temperature

1)Melting Point:The temperature at which a solid melts to form liquid at atmospheric pressure is called its melting point.

🔅Latent Heat Of Fusion :-

The amount of heat energy required to change 1kg of solid to its liquid state.

2)Boiling Point:The temperature at which a liquid boil to form vapours at atmospheric pressure is called its boiling point.

🔅Latent Heat Of Vaporisation:-

The amount of heat energy required to change 1kg of liquid to its gaseous state.

3)Sublimation:The change of solid directly into vapour on heating and vapour into solid on cooling without passing through the liquid state called sublimation.

Example:Camphor, Ammonium chloride, Nepthalene balls.

🔅Effect Of Change Of Pressure

If we compress a gas in a cylinder ,the distance between the particles of gas is reduced and finally gas is liquified.

LPG:Liquid Petroleum Gas

CNG:Compressed Natural Gas

🔅Evaporation:It is a surface phenomenon in which liquid changes into vapours at any temperature below its boiling point is called evaporation.

🔅Factors Affecting Evaporation

1)Exposed surface area

2)Temperature

3)Humidity

4)Wind

🔅Evaporation always causes cooling

The cooling caused by evaporation is based on the fact that when a liquid evaporates ,takes latent heat of vaporisation from surroundings which on loosing heat gets cool.

🔅Some Important Points :-

🔅The SI unit of mass is kilogram(kg).

🔅The SI unit of volume is cubic metre (m3).

🔅The common unit of measuring volume is litre (L) such that 1L equal 1dm3,1L equal 1000ml, 1ml equal 1cm3.

🔅The melting point of ice is 273.16K.The process of melting ,that is change of solid state into liquid state is also known as fusion.

🔅Kelvin is the SI unit of temperature, 0 degree celcius equal 273.16K.

🔅The pressure of air in atmosphere is called atmospheric pressure.