๐ Matter in Our
Surroundings – Humanized NCERT Notes (Part 1) ๐จ๐ซ๐
Class 9 Science Chapter 1 Notes ✨
Based on NCERT PDF uploaded by you
๐ Overview
Everything around us is made of matter ๐งช
✅ Air we breathe
✅
Water we drink
✅
Food we eat
✅
Plants, animals, stars, clouds
๐ Matter is anything
that:
✔️ Has mass
✔️
Occupies space
๐ Definition of Matter
Matter = Anything which has mass and volume.
๐️ Ancient Ideas About
Matter
๐ฎ๐ณ Indian
Philosophers – Panch Tatva
They believed all matter is made of 5 elements:
๐ฌ️ Air
๐
Earth
๐ฅ
Fire
๐
Sky
๐ง
Water
๐ฌ๐ท Greek
Philosophers
They also gave similar ideas about matter.
๐ฌ Physical Nature of
Matter
Scientists discovered that:
✅ Matter is made of tiny
particles
These particles are extremely small and cannot be seen
easily.
๐งช Activity 1 – Salt in
Water
Take water in a beaker and add salt.
Observation ๐
✔️ Salt disappears
✔️
Water level almost same
Conclusion ๐ฏ
Salt particles go into spaces between water particles.
๐ Matter particles have
spaces between them.
๐งช Activity 2 – Potassium
Permanganate
Few crystals color a large amount of water again and again.
Conclusion ๐ฏ
✔️ One crystal contains millions
of particles
✔️
Particles are very tiny
๐ก Characteristics of
Particles of Matter
1️⃣ Particles Have Space Between
Them
Examples:
☕ Tea
๐
Lemon water
๐ฅ
Milk in water
All mix because particles have empty spaces.
2️⃣ Particles Are Continuously
Moving
Particles never stay still.
They always move due to kinetic energy ⚡
๐งช Examples
๐ธ Smell of Perfume
You can smell perfume from far away.
๐ Perfume particles move
through air.
๐ฒ Hot Food Smell Reaches
Fast
Hot food smell spreads faster because heat increases
particle speed.
3️⃣ Diffusion
Diffusion = Intermixing of particles on their own.
Examples:
๐ธ Perfume in room
๐️
Ink spreading in water
๐
Food smell in air
4️⃣ Particles Attract Each Other
Particles pull each other with force.
This force is called:
๐ Force of Attraction
๐ Strength of Attraction
|
Substance |
Force |
|
Solids |
Maximum |
|
Liquids |
Medium |
|
Gases |
Minimum |
๐ง Trick to Remember
S L G
Strongest = Solid
Less = Liquid
Gone weak = Gas ๐
๐ง States of Matter
Matter exists in 3 common states:
๐ง Solid
๐ง
Liquid
๐ฌ️
Gas
๐งฑ Solid State
Properties of Solids
✔️ Fixed shape
✔️
Fixed volume
✔️
Hard / rigid
✔️
Cannot flow
✔️
Very little space between particles
✔️
Strong attraction force
Examples:
๐ช Chair
๐
Book
๐งฑ
Brick
๐ชจ
Stone
๐ง Liquid State
Properties of Liquids
✔️ Fixed volume
❌
No fixed shape
✔️
Take shape of container
✔️
Can flow
✔️
Moderate force of attraction
Examples:
๐ง Water
๐ฅ
Milk
๐ข️
Oil
๐ง
Juice
๐ฌ️ Gaseous State
Properties of Gases
❌ No fixed shape
❌
No fixed volume
✔️
Fill entire container
✔️
Highly compressible
✔️
Very weak attraction force
✔️
Move very fast
Examples:
๐ฌ️ Air
๐จ
Oxygen
๐ฅ
LPG
๐
CNG
๐ Difference Table
|
Property |
Solid |
Liquid |
Gas |
|
Shape |
Fixed |
No fixed |
No fixed |
|
Volume |
Fixed |
Fixed |
No fixed |
|
Flow |
No |
Yes |
Yes |
|
Compressibility |
Very low |
Low |
High |
|
Attraction |
Strong |
Medium |
Weak |
๐ฅ Change of State of
Matter
Matter can change from one state to another by:
๐ก️ Changing temperature
ุถุบุท Increasing or
decreasing pressure
๐ Interconversion of
States
๐ง Solid ⇄
๐ง
Liquid ⇄
๐ฌ️
Gas
Examples:
๐ง Ice → Water → Steam
๐ก️ Effect of Temperature
When temperature increases:
✔️ Particles gain kinetic energy ⚡
✔️
Move faster
✔️
Force of attraction becomes weaker
So matter changes state.
๐ง Melting / Fusion
Melting = Change of solid into liquid on heating.
Example:
๐ง Ice → ๐ง
Water
Melting Point
Melting Point = Temperature at which solid melts into
liquid.
0^\circ C = 273,K
๐ Ice melts at 0°C or
273 K
๐ก Important Note
During melting:
✔️ Temperature remains constant
✔️
Heat is used to break particle attraction
๐ฅ Latent Heat of Fusion
Latent Heat of Fusion = Heat required to convert 1
kg solid into liquid at melting point without temperature rise.
๐ง Boiling / Vaporisation
Boiling = Change of liquid into gas on heating.
Example:
๐ง Water → ☁️
Steam
Boiling Point
Boiling Point = Temperature at which liquid starts
boiling.
100^\circ C = 373,K
๐ Water boils at 100°C
or 373 K
๐จ Latent Heat of
Vaporisation
Heat required to convert 1 kg liquid into gas at
boiling point without temperature rise.
๐ก Why Steam Causes More
Burns?
Steam at 100°C contains extra latent heat.
๐ So steam gives more
heat than boiling water.
❄️ Sublimation
Sublimation = Direct change of solid into gas without
becoming liquid.
Examples:
๐งด Camphor
⚪
Naphthalene balls
๐ง
Dry ice
๐ Deposition
Deposition = Direct change of gas into solid.
Example:
❄️ Water vapour → Frost
๐ Temperature Conversion
To convert Celsius to Kelvin:
K = ^\circ C + 273
To convert Kelvin to Celsius:
^\circ C = K - 273
๐งช Effect of Pressure
When pressure increases:
✔️ Gas particles come closer
✔️
Gas can become liquid
Examples:
๐ฅ LPG cylinder
๐
CNG
๐ฅ
Oxygen cylinder
๐ซ️ Dry Ice
Solid carbon dioxide = Dry Ice
It changes directly into gas.
๐ Used in
cooling/storage.
๐จ Evaporation
Evaporation = Change of liquid into vapour at any
temperature below boiling point.
Example:
๐ Wet clothes drying
๐ง
Water disappearing from floor
๐ Difference: Boiling vs
Evaporation
|
Property |
Boiling |
Evaporation |
|
Temperature |
Fixed |
Any temperature |
|
Place |
Whole liquid |
Surface only |
|
Speed |
Fast |
Slow |
๐ฌ️ Factors Affecting
Evaporation
1️⃣ Surface Area ↑
More surface = faster evaporation
Example:
๐ Clothes spread out dry
faster
2️⃣ Temperature ↑
Higher temperature = particles move faster
3️⃣ Wind Speed ↑
Wind removes vapour quickly
๐ Clothes dry faster on
windy day
4️⃣ Humidity ↓
Less moisture in air = faster evaporation
❄️ Evaporation Causes Cooling
During evaporation:
✔️ Fast particles leave surface
✔️
Remaining liquid becomes cool
Examples:
๐งด Perfume on hand feels
cold
๐ฆ
Sweat cools body
๐บ
Matka water becomes cool
๐ Why Cotton Clothes in
Summer?
✔️ Cotton absorbs sweat
✔️
Sweat evaporates easily
✔️
Body feels cool
๐ง Why Water Drops Form
Outside Cold Glass?
Water vapour from air cools and condenses on glass surface.
๐ Forms droplets outside
glass.
๐ง Quick Tricks
Change of State Order
Solid → Liquid → Gas
Heat Increases Motion
Heat ↑ = Speed ↑
Cooling by Evaporation
Evaporation = Cool ๐
