CBSE class 9 complete chapter with all concepts explained

1. CLASS-IX CHEMISTRY
CHAPTER-1
MATTER IN OUR
SURROUNDING
Lecture-1
By- Tina Singh

2. INTRODUCTION:
 Everything in this universe is made up of material which scientists have
named “MATTER”.
Panch tatva = Air, Earth, Water, Fire and Sky.
Modern day Scientists have evolved two types of classification of matter
based on their physical and chemical nature.

3. PHYSICALNATUREOFMATTER:

4. 1. Matter is made up of particles.
2. The constituent particles of matter are very tiny and can
not be seen by naked eyes.

5. CHARACTERISTICSOFPARTICLESOFMATTER:

6. CHARACTERISTICSOFPARTICLESOFMATTER:
1) Particles have space between them.
2) Particles of matter are continuously moving.
3) Particles of matter attract each other.

7. STATESOFMATTER:
There are three states of matter: solid, liquid and gas.
These states arises due to the variation in the characteristics of the particles of
matter.
1. The Solid State:
 Definite shape/ are rigid.
 Distinct boundaries
 Fixed volumes.
 Negligible compressibility
 Example: paper, ice, wood
etc.

8. 2. The Liquid State:
No fixed shape.
Fixed volume.
Have fluidity
Solid, liquid and gases all can
diffuse into liquids.
Liquid disuse faster than solid
Example: water, petrol, aceton etc.
No fixed shape
No fixed volume
Great compressibility
Very fast diffusion
Example; oxygen, carbondiocide
etc.

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11. CLASS-IX CHEMISTRY
CHAPTER-1
MATTER IN OUR
SURROUNDING
Lecture-2
By- Tina Singh

13. CANMATTERCHANGEITSSTATE:
Yes as water exist in all three states.
solid – ice
liquid- water
gas – vapor
Matter can change their state on
changing the conditions of
temperature and pressure.

14. Effect of change of temperature:
The temperature at which solid melts to become a liquid at atmospheric pressure is
called its melting point.
The temperature at which liquid starts boiling at the atmospheric pressureis known as
its boiling point.
The heat absorbed at the state change does not show any rise in temperature and
considered as the latent heat.

15. Effect of change of pressure:

18. THANK YOU

19. CLASS-IX CHEMISTRY
CHAPTER-1
MATTER IN OUR
SURROUNDING
Lecture-3
By- Tina Singh

20. Effectofchangeoftemperatureandpressureonstateof
matter:

21. EVAPORATION:
The phenomenon of change of a liquid into
vapors at any temperature below its boiling
point is known as evaporation.
Factors affecting evaporation:
More is the Surface area more will be
evaporation.
Increase in Temperature increases the
evaporation.
Decrease in humidity decrease the
evaporation.
Wind speed, speed up the evaporation.

22. Howevaporationcausescooling?
During evaporation particles of the liquid absorb
energy from the surrounding to regain the energy
lost during evaporation. This absorption of energy
from the surrounding make the surroundings cool.

23. Whywewearcottonclothesinsummer?
As we know evaporation occurs at the surface,
therefore sweat from the body gets evaporated and
absorbs energy from the surrounding, leaving
behind the cooling effect. Cotton clothes are good
absorbers, hence absorbs the sweat and provide a
wider surface area foe evaporation.

24. Whydoweseewaterdropletsontheoutersurfaceofthe
glasscontainingicecoldwater?
The water vapor present
in the air on coming in
contact with the cold
glass of water looses
energy and gets
converted to liquid state,
which we see as water
droplets.

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