Class 9 Science
Chapter 1: Matter in Our Surroundings
NCERT Revision Notes
1. What is Matter?
Matter is anything that occupies space and has mass. Everything around us — air, water, stone,
chair, food — is made up of matter.
Characteristics of Particles of Matter:
• Particles of matter are very small in size.
• Particles of matter have spaces between them (interparticle space).
• Particles of matter are continuously moving (possess kinetic energy).
• Particles of matter attract each other (interparticle force of attraction).
Example: One crystal of KMnO4 (Potassium permanganate) dissolved in water keeps dividing into
smaller and smaller particles, showing how tiny matter particles are.
2. States of Matter
Matter exists in three states: Solid, Liquid, and Gas.
Property Solid Liquid Gas
Shape Fixed No fixed shape No fixed shape
Volume Fixed Fixed No fixed volume
Compressibility Very low Low Highly compressible
Fluidity Cannot flow Can flow Can flow
Interparticle Space Very small More than solid Very large
Force of Attraction Very strong Weaker Weakest
Kinetic Energy Lowest Moderate Highest
Examples Ice, stone, wood Water, milk, oil Air, steam, oxygen
3. Effect of Temperature — Change of State
On increasing temperature, particles gain kinetic energy, vibrate faster, and overcome
intermolecular forces — changing state.
Important Terms:
Chapter 1: Matter in Our Surroundings
NCERT Revision Notes
1. What is Matter?
Matter is anything that occupies space and has mass. Everything around us — air, water, stone,
chair, food — is made up of matter.
Characteristics of Particles of Matter:
• Particles of matter are very small in size.
• Particles of matter have spaces between them (interparticle space).
• Particles of matter are continuously moving (possess kinetic energy).
• Particles of matter attract each other (interparticle force of attraction).
Example: One crystal of KMnO4 (Potassium permanganate) dissolved in water keeps dividing into
smaller and smaller particles, showing how tiny matter particles are.
2. States of Matter
Matter exists in three states: Solid, Liquid, and Gas.
Property Solid Liquid Gas
Shape Fixed No fixed shape No fixed shape
Volume Fixed Fixed No fixed volume
Compressibility Very low Low Highly compressible
Fluidity Cannot flow Can flow Can flow
Interparticle Space Very small More than solid Very large
Force of Attraction Very strong Weaker Weakest
Kinetic Energy Lowest Moderate Highest
Examples Ice, stone, wood Water, milk, oil Air, steam, oxygen
3. Effect of Temperature — Change of State
On increasing temperature, particles gain kinetic energy, vibrate faster, and overcome
intermolecular forces — changing state.
Important Terms:
