Matter

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1. Introduction to Matter

• Definition of Matter:
  Matter is anything that occupies space and has mass. It forms the physical “stuff” around us—from the air we breathe to the objects we use.

• Key Idea:
  Every object, whether living or non-living, is composed of matter.

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2. Classification of Matter

• Based on Composition:

  • Pure Substances:
    Matter that has a uniform and definite composition. It can be an element (like oxygen) or a compound (like water).
  • Mixtures:
    Matter composed of two or more pure substances that are not chemically combined. Mixtures can be:
    • Homogeneous (uniform composition, e.g., saltwater)
    • Heterogeneous (non-uniform, e.g., a salad)

• Based on States of Matter:

  • Solids
  • Liquids
  • Gases

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3. States of Matter and Their Characteristics

a. Solids

• Properties:
  • Fixed shape and volume
  • Particles are tightly packed
  • Particles vibrate in place
• Examples: Wood, ice, iron

b. Liquids

• Properties:
  • Fixed volume, shape of container
  • Particles are close but can move
  • Exhibit fluidity
• Examples: Water, oil, milk

c. Gases

• Properties:
  • No fixed shape or volume
  • Particles move freely and are far apart
  • Exert pressure on container walls
• Examples: Air, oxygen, nitrogen

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4. Particle Arrangement and Movement

• Solids: Particles are tightly packed and vibrate in place
• Liquids: Particles are loosely packed and move past each other
• Gases: Particles are far apart and move freely in all directions

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5. Change of State (Phase Transitions)

• Melting: Solid → Liquid (on heating)
• Freezing: Liquid → Solid (on cooling)
• Evaporation: Liquid → Gas (from surface)
• Boiling: Liquid → Gas (throughout the liquid)
• Condensation: Gas → Liquid (on cooling)
• Sublimation: Solid → Gas (directly, e.g., camphor)
• Deposition: Gas → Solid (directly, e.g., frost)

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6. Physical and Chemical Properties

• Physical Properties: Can be observed without changing identity (e.g., color, boiling point)
• Chemical Properties: Observed during a chemical change (e.g., flammability, rusting)

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7. Importance of Understanding Matter

• Helps in understanding everyday phenomena
• Used in industrial and scientific processes
• Crucial in designing and using materials in different fields

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8. Summary

• Matter exists in three primary states: solid, liquid, gas
• Particles have motion and interact with each other
• States of matter change due to heat and pressure
• Understanding matter helps in science, industry, and daily life

Evaporation – Short Notes (Class 9)

1. Definition

Evaporation is the process of slow conversion of a liquid into vapour from its surface, at any temperature below boiling point.

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2. Daily Life Example

Drying of wet clothes

Water from ponds and puddles disappearing

Sweat drying from skin

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3. Key Features

Happens only at the surface

Takes place at any temperature

Slow and natural process

Uses heat from surroundings

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4. Factors Affecting Evaporation

Temperature: Higher temp = faster evaporation

Surface Area: Larger area = more evaporation

Humidity: More humidity = slower evaporation

Wind Speed: More wind = faster evaporation

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5. Evaporation Causes Cooling

When a liquid evaporates, it takes heat from the surface, causing cooling.

Examples:

Sweat cools our body

Water stays cool in an earthen pot

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6. Importance in Daily Life

Cooling effect (sweating, matka)

Drying clothes

Making salt from seawater

Used in coolers and fridges (indirectly)

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Matter in Our Surroundings – Short Notes (Class 9)

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1. What is Matter?

Anything that has mass and occupies space

Found in all forms — solid, liquid, gas

2. Characteristics of Particles of Matter

Made up of tiny particles

Particles have space between them

Particles are constantly moving

Particles attract each other

3. States of Matter

Solid: Fixed shape and volume, tightly packed particles

Liquid: No fixed shape, fixed volume, flows easily

Gas: No fixed shape or volume, highly compressible, free-moving particles

4. Diffusion

Mixing of particles of two substances

Faster in gases than liquids

Example: Smell of perfume spreads in a room

5. Interconversion of States of Matter

Solid ↔ Liquid: Melting / Freezing

Liquid ↔ Gas: Evaporation / Condensation

Solid ↔ Gas: Sublimation / Deposition

These changes are physical and reversible

6. Melting Point

Temperature at which a solid changes to liquid

Melting point of ice = 0°C

7. Boiling Point

Temperature at which liquid changes to gas

Boiling point of water = 100°C

8. Latent Heat

Heat required to change the state without temperature change

Latent heat of fusion: Solid → Liquid

Latent heat of vaporisation: Liquid → Gas

9. Sublimation

Solid directly changes to gas without becoming liquid

Example: Camphor, naphthalene, dry ice

10. Evaporation

Slow change from liquid to gas at all temperatures below boiling point

Happens only at surface

Uses heat from surroundings

Factors affecting evaporation:

1. Temperature

2. Surface area

3. Humidity

4. Wind speed

Evaporation causes cooling

Example: Sweat cools the body, matka water stays cool

11. Condensation

Gas changes to liquid on cooling

Example: Water droplets on a cold glass

12. Freezing

Liquid changes to solid on cooling

Reverse of melting

Example: Water turns to ice in freezer

13. Effect of Pressure on Matter

Increasing pressure → Gases become liquids

Example: LPG and CNG cylinders are compressed gases

14. Plasma and Bose-Einstein Condensate (For Info Only)

Plasma: Ionized gas (found in stars, neon signs)

Bose-Einstein Condensate (BEC): Supercooled atoms behaving as a single unit

15. Important Temperatures

Melting point of ice: 0°C

Boiling point of water: 100°C

Room temperature: ~25°C

16. Summary (One-Liners for Revision)

Matter has mass and occupies space

Three main states: Solid, liquid, gas

Matter changes state due to heat or pressure

Evaporation causes cooling

Interconversion of states.

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