Class 9 Science – Complete Exam‑Oriented Notes
(CBSE / NCERT)
Chapter 1: Matter in Our Surroundings
1. What is Matter?
• Matter: Anything that has mass and occupies space.
• Ancient Indian philosophers classified matter into Pancha Tatva (earth, water, air, fire, sky).
2. Physical Nature of Matter
Key Points: - Matter is made of tiny particles. - Particles of matter have spaces between them. - Particles
are in constant motion (diffusion). - Particles attract each other.
Example: Smell of perfume spreads due to diffusion.
3. States of Matter
State Shape Volume Compressibility
Solid Fixed Fixed Negligible
Liquid No fixed shape Fixed Small
Gas No fixed shape No fixed volume High
4. Change of State
• Melting point: Temperature at which solid → liquid
• Boiling point: Temperature at which liquid → gas
• Latent heat of fusion: Heat required to change solid into liquid at melting point.
• Latent heat of vaporisation: Heat required to change liquid into gas at boiling point.
5. Effect of Change of Temperature
• Increase in temperature → increase in kinetic energy.
6. Evaporation
Factors affecting evaporation: - Surface area - Temperature - Humidity - Wind speed
Cooling effect: Evaporation causes cooling.
1
, Examiner Keywords: diffusion, latent heat, sublimation
Chapter 2: Is Matter Around Us Pure?
1. Pure Substance
• A pure substance consists of a single type of particles.
2. Mixtures
Types: - Homogeneous (solutions) - Heterogeneous
3. Solution
• Solute + Solvent = Solution
• Concentration of solution = (Mass of solute / Mass of solution) × 100
4. Colloids
• Heterogeneous mixture
• Show Tyndall effect
5. Suspension
• Particles settle down on standing
6. Separation Techniques
• Filtration
• Evaporation
• Distillation
• Chromatography
Important Scientist: - Tyndall – Tyndall effect
Chapter 3: Atoms and Molecules
1. Laws of Chemical Combination
• Law of Conservation of Mass – Antoine Lavoisier (1789)
• Law of Constant Proportions – Joseph Proust
2. Dalton’s Atomic Theory (1808)
Postulates: - Matter made of atoms - Atoms are indivisible
2
(CBSE / NCERT)
Chapter 1: Matter in Our Surroundings
1. What is Matter?
• Matter: Anything that has mass and occupies space.
• Ancient Indian philosophers classified matter into Pancha Tatva (earth, water, air, fire, sky).
2. Physical Nature of Matter
Key Points: - Matter is made of tiny particles. - Particles of matter have spaces between them. - Particles
are in constant motion (diffusion). - Particles attract each other.
Example: Smell of perfume spreads due to diffusion.
3. States of Matter
State Shape Volume Compressibility
Solid Fixed Fixed Negligible
Liquid No fixed shape Fixed Small
Gas No fixed shape No fixed volume High
4. Change of State
• Melting point: Temperature at which solid → liquid
• Boiling point: Temperature at which liquid → gas
• Latent heat of fusion: Heat required to change solid into liquid at melting point.
• Latent heat of vaporisation: Heat required to change liquid into gas at boiling point.
5. Effect of Change of Temperature
• Increase in temperature → increase in kinetic energy.
6. Evaporation
Factors affecting evaporation: - Surface area - Temperature - Humidity - Wind speed
Cooling effect: Evaporation causes cooling.
1
, Examiner Keywords: diffusion, latent heat, sublimation
Chapter 2: Is Matter Around Us Pure?
1. Pure Substance
• A pure substance consists of a single type of particles.
2. Mixtures
Types: - Homogeneous (solutions) - Heterogeneous
3. Solution
• Solute + Solvent = Solution
• Concentration of solution = (Mass of solute / Mass of solution) × 100
4. Colloids
• Heterogeneous mixture
• Show Tyndall effect
5. Suspension
• Particles settle down on standing
6. Separation Techniques
• Filtration
• Evaporation
• Distillation
• Chromatography
Important Scientist: - Tyndall – Tyndall effect
Chapter 3: Atoms and Molecules
1. Laws of Chemical Combination
• Law of Conservation of Mass – Antoine Lavoisier (1789)
• Law of Constant Proportions – Joseph Proust
2. Dalton’s Atomic Theory (1808)
Postulates: - Matter made of atoms - Atoms are indivisible
2
