Here We have provided Matter in Our Surroundings Class 9 Notes. Matter in Our Surroundings Class 9 Notes will help you in understanding the chapter better & will be helpful in your exam preparation.
Matter in our surroundings class 9 science chapter 1 notes
Matter
Anything which occupies space, and has mass is called matter.
Ex- Tron, brick, aluminum, etc.
Physical Nature of matter :
- Matter is composed of tiny particles known as atoms.
- The number of atoms in a matter is very large.
- Atoms are very small in size that we can not see it with the naked eyes.
- Atoms are composed of three sub-atomic particles called electron, proton and neutron
- Electron is discovered by JJ Thomson in 1897.
- Proton was discovered by E. Gold Stein in 1886.
- Neutron was discovered by James Chadwick in 1932.
Characteristics of Particles
- The particles of matter are very small in size.
- They have space between them.
- The particles of matter are, continuously moving in a zig-zag motion.
- The particles of matter attract each other.
States of matter
There are five states of matter:-
- Solids
- liquids
- gases
- Plasma
- Bose-Einstien condensate
(a) Solids:-
- Solids have definite shapes and fixed volumes.
- The intermolecular force of attraction is strong.
- Solids have negligible compressibility.
- Solids are rigid.
- Solids cannot flow.
(b) Liquids:-
- Liquids have no fixed shape but have fixed volume.
- Liquids can be compressed.
- Liquids are not rigid
- Liquids can flow.
- The intermolecular force of attraction is not as strong as solids.
(c) Gases: –
- Gases have no fixed shape.
- Gases have no fixed volume.
- It can be compressed much.
- Gases can flow.
- The intermolecular force of attraction is very weak.
Rigidity:-
The tendency to maintain shape when subjected to outside force is called rigidity.
Diffusion :
Intermixing of particles of two different types of matter on their own is called diffusion.
Diffusion becomes faster on heating
Note: If we increase the temperature, the kinetic energy of the particles also increases.
Density
The mass per unit volume is called density.
The SI unit of density is kgm-3.
It is denoted by Rho(ρ).
Its formula = ρ = m/v
Plasma:-
Plasma is the fourth state of matter, it does not bit into any of the known three states of matter.
Plasma state consists of highly ionized gas in which the particles exist in a super energetic and super excited state.
The light in the sun, stare is due to plasma.
Bose-Einstein condensate:-
In 1920, the Indian scientist Satendarnath bose on the basis of his statical calculation gave the concept of the fifth state of matter. Einstein too predicted the possibility of such a state.
Later, the three American scientists succeeded in this state by super cooling a gas of extremely low density.
The BEC is the fifth state of matter.
Changing states of matter:
(i) Effect of change of temperature:
On heating, the kinetic energy of the particles increases, this makes the particles vibrate rapidly. At a certain temperature, the kinetic energy becomes sufficient to overcome the binding forces of particles. The particles then leave their position and the state gets changed.
(ii) Effect of change of Pressure:-
In increase in pressure brings the particles of a Substance closer, as a result, the inter particular space decreases and at the same time cohesive force increases. This leads to a change in physical state.
Note: Pressure is directly proportional to temperature.
Changing solid to liquid:
(i) By increasing temperature and decreasing pressure.
(ii) The process of conversion of solid to liquid is called fusion.
Changing liquid to solid:-
- By decreasing temperature and increasing pressure.
- The process of conversion of liquid to solid is called freezing.
Changing liquid to gas:-
(i) By increasing temperature and decreasing pressure.
(ii) The process of conversion of liquid to gas is called vaporisation.
Changing gas to liquid:-
(i) By decreasing temperature and increasing pressure.
(ii) The process of conversion of gas to liguid is called condensation.
Sublimation:-
The change of state directly from solid to gas or gas to solid without changing into liquid, this process is called Sublimation.
Ex- dry ice, camphor, naphthalene, ammonia, etc.
Inter-convertible states of matter:-
Latent heat:- (Hidden Energy)
The energy or heat required for a substance to gain its melting point or boiling point or to change its state is called latent heat.
(i) Latent heat of fusion
The amount of heat energy required to change 1 kg of solid into liquid at its melting point.
The latent heat of the fusion of ice is 3.35×105 Jkg-1
(ii) Latent heat of vaporisation
The heat energy required to change 1kg of liquid to gas at atmospheric pressure at its boiling point.
The latent heat of water is 22.6×105 J kg-1
SI unit of:
Ideal energy= Joule
Evaporation
The conversion of a liquid into its vapour either by exposing the liquid to air at room temperature or by hitting it below its boiling point is known as evaporation. Evaporation is a surface phenomenon.
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