⬆️ TOP EDUCATION ⬆️
CBSE
CLASS 9 SCIENCE
CHAPTER 1 MATTER IN OUR SURROUNDINGS
NOTES
1. Matter: Anything that occupies space and has mass is called matter.
👉Matter is composed of tiny particles called atoms and molecules.
2. States of Matter:
👉Solid: Definite shape and volume, particles are closely packed and have strong intermolecular forces.
👉Liquid: Definite volume but no definite shape, particles are close but can move past each other.
👉Gas: No definite shape or volume, particles are far apart and have weak intermolecular forces.
3. Change of State:
Melting: Solid to liquid.
Freezing: Liquid to solid.
👉Evaporation: Liquid to gas at any temperature.
👉Condensation: Gas to liquid.
👉Sublimation: Solid directly to gas or vice versa without passing through the liquid state.
4. Physical Properties of Matter:
👉Colour, odor, taste, hardness, density, boiling point, melting point, etc.
5. Characteristics of Particles of Matter:
👉Particles of matter have space between them.
👉They are constantly moving and have kinetic energy.
👉The particles of matter attract each other due to intermolecular forces.
6. The Particle Nature of Matter:
👉Matter is made up of particles.
👉Particles of matter are very small and can't be seen with the naked eye.
👉Particles have spaces between them.
7. The Effect of Change of Temperature:
👉Increase in temperature causes particles to move faster.
👉Decrease in temperature causes particles to move slower.
8. The Effect of Change of Pressure:
👉Increase in pressure compresses the particles and reduces the space between them.
👉Decrease in pressure expands the particles and increases the space between them.
9. Evaporation:
👉The process of conversion of a liquid into vapor at any temperature.
👉Evaporation occurs from the surface of a liquid.
👉Factors affecting evaporation: temperature, surface area, wind speed, humidity.
10. Condensation:
👉The process of conversion of a gas into a liquid.
👉It occurs when a gas loses heat energy and converts into a liquid.
11. Sublimation:
👉The process of conversion of a solid directly into a gas or vice versa without passing through the liquid state.
👉Examples: ammonium chloride, camphor, dry ice (solid carbon dioxide).
12. Diffusion:
👉The process by which particles of a substance move from an area of higher concentration to an area of lower concentration.
👉Diffusion occurs due to the random motion of particles.
⭐Remember to refer to your textbook and class notes for detailed explanations, diagrams, and examples related to each topic.
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