Class 9 Science — Chapter 1
Matter in Our Surroundings | Exam-Oriented Revision Notes
1. What is Matter?
Matter is defined as anything that has mass and occupies space (volume).
Examples: Air, water, stone, wood, milk, hydrogen, oxygen, etc.
Characteristics of Particles of Matter:
• Extremely Small: Particles of matter are microscopic in size.
• Interparticle Space: Particles have spaces between them.
• Continuous Motion: Particles are constantly moving (possess kinetic energy).
• Mutual Attraction: Particles exert forces of attraction on each other.
2. States of Matter
Liquid (e.g., Water,
Property Solid (e.g., Ice, Stone) Gas (e.g., Air, Oxygen)
Milk)
Shape Fixed shape No fixed shape No fixed shape
Volume Fixed volume Fixed volume No fixed volume
Very low (Almost
Compressibility Low Highly compressible
incompressible)
Particle Least (Vibrates at fixed Maximum (Moves freely &
Moderate (Can flow)
Movement position) rapidly)
Interparticle
Minimum Moderate Maximum
Space
Force of
Strongest Moderate Weakest
Attraction
3. Interconversion of States of Matter
Process Transition Example
Melting / Fusion Solid → Liquid Ice → Water
Vaporisation Liquid → Gas Water → Water Vapour
Condensation Gas → Liquid Water Vapour → Water
Page 1 of 3
Matter in Our Surroundings | Exam-Oriented Revision Notes
1. What is Matter?
Matter is defined as anything that has mass and occupies space (volume).
Examples: Air, water, stone, wood, milk, hydrogen, oxygen, etc.
Characteristics of Particles of Matter:
• Extremely Small: Particles of matter are microscopic in size.
• Interparticle Space: Particles have spaces between them.
• Continuous Motion: Particles are constantly moving (possess kinetic energy).
• Mutual Attraction: Particles exert forces of attraction on each other.
2. States of Matter
Liquid (e.g., Water,
Property Solid (e.g., Ice, Stone) Gas (e.g., Air, Oxygen)
Milk)
Shape Fixed shape No fixed shape No fixed shape
Volume Fixed volume Fixed volume No fixed volume
Very low (Almost
Compressibility Low Highly compressible
incompressible)
Particle Least (Vibrates at fixed Maximum (Moves freely &
Moderate (Can flow)
Movement position) rapidly)
Interparticle
Minimum Moderate Maximum
Space
Force of
Strongest Moderate Weakest
Attraction
3. Interconversion of States of Matter
Process Transition Example
Melting / Fusion Solid → Liquid Ice → Water
Vaporisation Liquid → Gas Water → Water Vapour
Condensation Gas → Liquid Water Vapour → Water
Page 1 of 3
