Class 9 Chapter 1 Matter in Our Surroundings

 Matter: Anything that has mass and occupies space.

 Key Points:

• Matter is made up of particles
• Particles are in continuous motion
• There is space between particles
• Particles attract each other

 Examples:

• Air
• Water
• Stone
• Book

 Characteristics of Particles of Matter:

1. Very small in size
2. In constant motion
3. Have space between them
4. Show force of attraction

 States of Matter:

1. Solid
   • Fixed shape and volume
   • Particles are tightly packed
2. Liquid
   • Fixed volume, no fixed shape
   • Particles are less tightly packed
3. Gas
   • No fixed shape and volume
   • Particles are far apart

Physical Nature of Matter :- 

Matter is made of particles:-

Matter consists of very small particles.

Characteristics of particles:-

1.Have space between them

    Example: Sugar dissolves in water

2.Are continuously moving:-

   Brownian motion

3.Attract each other:-

   Strong in solids

   Weak in gases

States of Matter

• Solid: Fixed shape & volume (strong attraction)
• Liquid: Fixed volume, no fixed shape
• Gas: No fixed shape & volume (very weak attraction)
• 
  

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 Diffusion

• Particles mix on their own
  • Fastest in gases, slowest in solids