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Matter in our surroundings: Class 9 Notes


Matter In our surroundings class 9 notes

Matter in our surroundings Class 9 Notes:

If you are wandering here and there matter in our surrounding notes then you are at right place. Matter in our surroundings class 9 notes will help you in revision and preparing for the final examinations. Here we included definition and characteristics of matter, diffusion and its application, Brownian motion, States of matter, all the three states of matter and their inter-conversion, evaporation, SI units of basic physical quantities.


  • Anything in this universe that has mass and occupies space is matter.
  • Or simply, anything having mass as well as volume also can be perceived through our senses are matters.
  • For example: Book, pencil, phone or anything around you is matter.
  • You will get the whole revision sheet under Matter in our surroundings class 9 notes.

Composition of matter:

  • Indian philosophers at early ages suggested that every living or non-living thing is made up of “panch tatva” which designates air, earth, fire, sky and water.
  • Modern scientists have clarified the same in different way. According to them, matter is made up of small particles.

Classification of matter:

 Matter is classified into different categories on the basis of its physical nature as well as chemical properties. Before defining different physical and chemical properties let us first consider the particle nature of matter. Chemical properties are not included in matter in our surroundings class 9 notes.

Characteristics of particles of matter:

  • Particles of matter are very small.
  • There are spaces between the particles.
  • They are continuously moving thus possess kinetic energy.
  • There is force of attraction between the particles.

Physical states of matter:

On the basis of physical nature of matter, it is classified into five different states. However, in Matter in our surroundings class 9 notes, we will read only main three states.

  • Solid state
  • Liquid State
  • Gaseous state
  • Plasma state
  • Bose-Einstien condensate

Difference table of solid, liquid, gaseous state:

Properties Solid state Liquid state Gaseous state
Space b/w
Particles are closely
packed in this state.
Constituent particles
are loosely packed.
Constituent particles
are far apart.
Force of
Very strong force of
attraction b/w particles
of solid state.
Weaker force of
attraction as compared
to solid state.
Much weak force
of attraction.
Shape &
Have definite shape
and fixed volume.
Don’t have definite
shape but have
fixed volume.
Neither have fixed
shape nor fixed volume.
Density They have high
Less density as
compared to solid state.
Very low density.
Diffusion It doesn’t diffuse. Liquid diffuses. It also diffuses.
Compression Incompressible. Almost incompressible. Highly compressible.
The constituent
particles possess a
little kinetic energy.
Its particle have kinetic
energy a little more
than that in solids.
The kinetic energy of
particles are very
high in gases.

Matter in our surroundings class 9 notes mentioned all the important properties based differences.


  • The intermixing of particles of two different types of matter on their own (due to motion of particles) is said to be
  • As the temperature of substance increased, the rate of diffusion also increases.
  • The diffusion of one substance into another substance continues until a uniform mixture is formed.
  • Diffusion takes place in solid, liquid as well as gases.

Applications of diffusion:

As diffusion takes place in all the three states so let’s read each separately in Matter in our surroundings class 9 notes:

  1. Diffusion in solid in liquid:
  • When potassium permanganate is added to a beaker filled with water, the colour of water slowly turns purple.
  • As both water and crystals are made up of particles and they have space between its particles and the particles of one occupies the space of the other (particles keep moving so the whole water turns purple). Thus diffusion takes place.
  1. Diffusion of two gases:
  • Gases have highest kinetic energy among the three states. So it moves fastest.
  • The smell of the cooking vegetable in the mom’s kitchen soon comes in your nose is due to the diffusion of gases.
  • As the gas or vapour from the cooking vessel moves in all direction and indulged in the vast space between particles of air.
  1. Diffusion of two solids:
  • When blocks of two metal are bound together tightly and kept undisturbed for a few years, then we find that the particles of one metal have diffused into the other metal.

Brownian movement:

The zig-zag motion of the particles in a fluid is said to be Brownian motion. In matter in our surroundings class 9 notes you are provided with what the actual syllabus is. For analysis prefer NCERT books.

Inter-conversion between states of matter:

All the three states of matter can be interchanged to one another. Let us take an example of water as it exists in all the three states, in solid state, it appears as ice and in liquid state, it resides as water whereas in gaseous state it is present in the form of water vapour. Matter in our surroundings class 9 notes contains the informative assesment of states of matter.

States of mater can be interchanged by two processes:

  1. By changing temperature
  2. By Changing Pressure

Effect of change of temperature:

Temperature plays a critical role in interchange of states. Here in matter in our surroundings class 9 notes, there are some inter-conversion by change in temperature:

  1. Solid to liquid (Melting):
  • The conversion of solid state of a substance into liquid is said to be melting or fusion.
  • The temperature at which solid melts to form liquid at the atmospheric pressure is its melting point.
  • When we increase temperature of solids, the kinetic energy of the particles increases which breaks forces of attraction between the particles thus, solid gets converted to a liquid.
  • Melting point of ice is 0oc.
  1. Liquid to gas (Evaporation):
  • The process of change of a liquid substance into gas on heating is called boiling.
  • At the atmospheric pressure, the temperature at which a liquid boils and converts to gas is called its boiling point.
  • When we heat a liquid the kinetic energy of its particles increases as high as in a gas, thus liquid converts to a gas.
  • Boiling point of water is 100oC.

Factors affecting the rate of evaporation:

  • If surface area increases rate of evaporation also increases.
  • Evaporation rate also increases with an increase in temperature.
  • The rate of evaporation increases with Decrease in the humidity.
  • It also increases with increase in wind speed.
  • There are more factors associated with it but as per the syllabus under matter in our surroundings class 9 notes its enough.
  1. Gas to liquid (condensation):
  • The process by which on cooling a gas turns into a liquid at a specific temperature is called condensation or liquefaction.
  • Condensation is the reverse process of vaporization.
  • When we cool water vapour, its kinetic energy decreases. The particles come closer to each other thus gets converted into liquid.
  • This type of conversion takes place in water cycle.
  1. Liquid to solid (Freezing):
  • The conversion of a liquid into solid by decreasing its temperature is said to be freezing.
  • The temperature at which liquid changes to solid state is said to be the freezing point.
  • The kinetic energy of a liquid is less and on cooling it the kinetic energy becomes negligible and particle does not move. Thus liquid converts into solid. 
  • The matter in our surroundings class 9 notes is designed to make your efforts in the right way.
  1. Gas to Liquid (Sublimation):
  • The method of converting solid state to directly gaseous state without changing into intermediate liquid state is said to be sublimation.

Difference between Evaporation and boiling:

Difference tables are exclusively added in Matter in our surroundings class 9 notes to get better understanding of the chapter.

Evaporation Boiling
Evaporation is a surface
Boiling is a bulk (body)
It is a slow process. It is a rapid process.
Evaporation occurs at all
temperatures but below
the boiling point.
Boiling occurs at a fixed

Effect of change of pressure:

  • The state of matter can be changed by changing the pressure.
  • We can liquefy gases by applying pressure and reducing temperature.
  • Under high pressure, we store Solid carbon dioxide (CO­2).
  • Here is sticky revision as it belongs to matter in our surroundings class 9 notes.

Latent Heat of Fusion and vaporization:

  • We can define latent heat as the heat required to convert solid into liquid or vapour, or liquid into vapour, without change of temperature.
  • This does not increase the temperature of a substance.
  • Latent heat of fusion: At atmospheric pressure, the heat energy needed in converting 1 kilogram of a solid into liquid, at its melting point is latent heat of fusion.
  • Latent heat of vaporization: At atmospheric pressure, the heat energy needed to convert 1 kilogram of liquid into gas at its boiling point, is said to be the latent heat of vaporization.
  • For better revision read matter in our surroundings class 9 notes.

Temperature scale:

  • The SI unit of temperature in Kelvin (K).
  • T (K) = T(_⁰C) + 273K
  • Kelvin scale is considered better than celcius.

Learn for better exams.Also read math formula.


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