Matter in Our Surroundings Class 9 Study Notes

Class 9 Science Chapter 1 “Matter in our Surroundings” Study Notes are available here for students and teachers for education purpose.

Class 9 Science Chapter 1 “Matter in Our Surroundings”

Class 9 Science Chapter 1 is “Matter in Our Surroundings”. This first chapter of Class 9 Science is very useful for exam point of view. This chapter consists of the topics – Matter, Characteristics of Particles of Matter, States of Matter, Diffusion, Melting Point, Boiling Point, Latent heat , Factors affecting to increase the rate of evaporation.

Science Chapter 1 “Matter in Our Surroundings” Class 9 Study Notes

Chapter Chapter 1 : Matter In Our Surroundings
SubjectScience
Study MaterialStudy Notes ( Short Notes)
Class 99 ( Class – IX )
Text bookScience ( NCERT Text Book for Class 9 )

Class 9 Science Chapter 1 “Matter In Our Surroundings” ( Study Notes )

1. Matter : Anything that occupies space and has mass is known as Matter.

2. Characteristics of Particles of Matter
• Particles of matter have space between them.
• Particles of matter are continuously moving.
• Particles of matter attract each other.

3. States of Matter
There are mainly three states of matter-
• Solid State
• Liquid State
• Gaseous State
The states of matter are inter-convertible. The state of matter can be changed by changing temperature or pressure.
Other states of matter – Bose Einstein Condensate and Plasma

4. The Solid State
• Solids have a fixed shape and fixed volumes.
• Solids can not be compressed much.
• Solids have high densities.
• Solids do not flow.
• Particles in Solids are closely packed.

5. The Liquid State
• Liquids do not have a fixed shape but have a fixed volume.
• Liquids can not be compressed much.
• Liquids have moderate to high densities. They are less dense than solids.
• Liquids generally flow easily.
• Particles in solids have space between them.

6. The Gaseous State
• Gases neither have a fixed volume nor fixed shape
• Gases can be compressed easily.
• Gases have very low density.
• Gases can flow easily.
• Particles in gases are very far from each other.

7. Diffusion : The spreading out and mixing of a substance with another substance due to the motion of its particles is known as Diffusion.
Note – On heating, Diffusion becomes faster.

8. Melting Point : A temperature at which a solid melts to become a liquid at the atmospheric pressure is known as its melting point.
The melting point of a solid is an indication of the strength of the force of attraction between its particles.

9. Boiling Point : The temperature at which a liquid starts boiling at the atmospheric pressure is known as its boiling point.
Note – Boiling is a bulk phenomenon.

10. Latent Heat : The heat energy which has to be supplied to change the state of a substance is called its Latent Heat. The word latent means hidden.

11. Latent Heat of Fusion : The amount if heat energy that is required to change 1 kg of solid into liquid at atmospheric pressure at its melting point is known as the latent heat of fusion.

12. Latent Heat of Vaporisation : The amount of heat energy that is required to change 1 kg of liquid into steam at atmospheric pressure at its boiling point is known as the latent heat of vaporisation.
Note – Latent heat does not cause rise in temperature of substance.

13. Applying pressure and reducing temperature can liquify the gases.

14. Evaporation : The phenomenon of change of a liquid into vapours at any temperature below its boiling point is called evaporation.

15. Factors affecting to increase the rate of evaporation
• An increase of surface area : If the surface area is increased, the rate of evaporation increases
• An increase of temperature : With the increase of temperature, more number of particles get enough kinetic energy to go into the vapour state. Hence the rate of evaporation increases.

• A decrease in humidity : If the amount of water in air is high, the rate of evaporation decreases. If the amount of water in air is low, the rate of evaporation increases.
• An increase in wind speed : With the increase in wind speed, the particles of water vapour move away with the wind, decreasing the amount of water vapour in the surrounding. Hence the rate of evaporation increase.

16. Density : The mass per unit volume of a substance is known as Density.
Density = mass/volume

17. Fusion : The process of melting, that is, change of solid state into liquid state is also known as fusion.

18. Interconversion of three states of matter.

interconversion of matte - matter in our surroundings
Interconversion of three states of matter.

19. Atmosphere (atm) : atm is a unit of measuring pressure exerted by a gas. The unit of pressure is Pascal (Pa): 1 atmosphere = 1.01 × 105 Pa.

20. Atmospheric Pressure : The pressure of air in atmosphere is called atmospheric pressure. The atmospheric pressure at sea level is 1 atmosphere, and is taken as the normal atmospheric pressure.

21. Humidity : The amount of water vapour present in air is known as Humidity.

22. Sublimation : The change of solid state directly to gaseous state without going through liquid state is known as Sublimation.

23. Important Units of some quantities
• 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)

24. Celsius to Kelvin conversion Formula
Kelvin = Celsius + 273.15
K = C + 273.15

25. Kelvin to Celsius conversion Formula
Celsius = Kelvin – 273.15
C = K – 273.15