๐งช Chapter 7 – Particulate Nature of Matter
๐ Introduction
Matter exists in three main forms:
- ๐งฑ Solid
- ๐ง Liquid
- ๐ฌ️ Gas
๐ค Think About It:
- Why can we pile sand but not water?
- How does air give weight to a balloon?
๐ These questions are explained by the particle nature of matter
๐ฌ 7.1 What is Matter Composed of?
๐งช Experiments & Observations
๐ชจ Chalk Experiment
- Break chalk → smaller pieces
๐ Shows matter is made of tiny particles
๐ฌ Sugar in Water
- Sugar disappears but:
- taste remains
๐ Proves:
- particles exist
- particles mix with each other
๐ Key Points:
- Matter is made of extremely small particles
- Particles cannot be seen even with ordinary microscope
๐ง Interparticle Spaces
- There are spaces between particles
- Sugar particles fill spaces between water particles
⚛️ 7.2 What Decides Different States of Matter?
๐ Main Factor:
Interparticle Forces of Attraction
๐ Depends on:
- Distance between particles
- Strength of attraction
๐ This decides whether matter is:
- Solid
- Liquid
- Gas
๐️ Our Scientific Heritage
- Acharya Kanad
- Introduced idea of:
⭐ Parmanu (Atom)
๐งฑ 7.2.1 Solid State
๐ Properties:
- Particles closely packed
- Strong attraction
- Fixed shape & volume
๐ Movement:
- Only vibration, no free movement
๐ฅ Heating Effect:
- Vibrations increase
- At melting point → solid → liquid
๐ก️ Melting Point:
Temperature at which solid changes into liquid
๐ Examples:
- Ice → 0°C
- Urea → 133°C
- Iron → 1538°C
๐ง 7.2.2 Liquid State
๐ Properties:
- Particles less tightly packed
- No fixed shape (takes container shape)
- Fixed volume
๐ Movement:
- Particles can move within liquid
๐ฅ Heating:
- At boiling point → liquid → gas
๐จ Evaporation:
- Happens at all temperatures
- Only from surface
๐ฌ️ 7.2.3 Gaseous State
๐ Properties:
- Particles very far apart
- Very weak attraction
๐ Movement:
- Free movement in all directions
๐ Shape & Volume:
- No fixed shape
- No fixed volume
๐ Important:
Liquids + Gases = Fluids (can flow)
๐ 7.3 Interparticle Spacing
๐น Solids:
- Minimum spacing
๐น Liquids:
- More spacing
๐น Gases:
- Maximum spacing
๐งช Examples:
๐ฌ Sugar in Water:
- Dissolves → fills spaces
๐️ Sand in Water:
- Does NOT dissolve
- Settles at bottom
๐ Key Point:
๐ Spaces are empty (not filled with air)
๐ 7.4 Movement of Particles
๐ง 1. In Liquids
๐งช Example:
- Potassium permanganate spreads in water
๐ก️ Observation:
- Spreads faster in hot water
๐ Heat increases particle motion
๐ฌ️ 2. In Gases
๐ฏ️ Example:
- Incense stick smell spreads in room
๐ Shows particles move freely
๐งผ 3. Everyday Example
- Soap removes oil because:
- one side attaches to oil
- other side attaches to water
๐ฅ Thermal Energy and Change of State
๐ Thermal Energy:
Energy that affects particle movement
๐งฑ Solids:
- Low energy
- Strong attraction
- Only vibration
๐ง Liquids:
- Medium energy
- Particles move
๐ฌ️ Gases:
- High energy
- Free movement
๐ฅ Effect of Heating:
- Increases energy
- Causes:
- Melting
- Boiling
- Evaporation
๐ Particle Nature of Matter (Summary Table)
State | Spacing | Packing | Attraction | Movement | Shape | Volume |
Solid | Minimum | Closely packed | Maximum | Vibrations only | Fixed | Fixed |
Liquid | More | Loosely packed | Weaker | Limited movement | Not fixed | Fixed |
Gas | Maximum | Free | Negligible | Free movement | Not fixed | Not fixed |
๐ Snapshots (Quick Revision)
⚡ One-Line Points
- Matter is made of tiny particles
- Particles have spaces and attraction
- Solids:
- Strongest forces
- Fixed shape & volume
- Liquids:
- Weaker forces
- Fixed volume
- No fixed shape
- Gases:
- Very weak forces
- No fixed shape & volume
- Heating:
- increases motion
- changes state
๐ฏ Final Conclusion
Matter behaves differently because of:
๐ Particle Arrangement + Forces + Energy
๐ Final Formula:
More Energy → More Movement → Change of State
๐ง Learning Outcome:
- Understand structure of matter
- Explain states of matter
- Apply concept in daily life
