Chapter 1: Matter in Our Surroundings
1.1 Physical Nature of Matter
Everything in the universe is made up of material which scientists have named "matter". Matter occupies space and has mass.
Key Property
Matter is made up of particles. These particles are very small – they are small beyond our imagination!
1.2 States of Matter
Matter around us exists in three different states: Solid, Liquid, and Gas.
| Property | Solid | Liquid | Gas |
|---|---|---|---|
| Shape | Fixed | No fixed shape | No fixed shape |
| Volume | Fixed | Fixed | No fixed volume |
| Compressibility | Negligible | Low | High |
1.3 Can Matter Change its State?
Latent Heat
The heat energy which has to be supplied to change the state of a substance without raising its temperature.
- Melting Point: 273.15 K (0°C).
- Boiling Point: 373 K (100°C).
- Sublimation: Direct change from solid to gas (e.g., Camphor).
1.4 Evaporation
The phenomenon of change of liquid into vapours at any temperature below its boiling point is called evaporation.
Fact: Evaporation causes Cooling
Particles of liquid absorb energy from the surroundings to regain the energy lost during evaporation.
Key Measurable Quantities
| Quantity | Unit | Symbol |
|---|---|---|
| Temperature | Kelvin | K |
| Volume | cubic metre | m³ |
| Pressure | Pascal | Pa |