1. Physical Nature of Matter
Matter is made up of particles. These particles are very small and have spaces between them.
They are continuously moving and attract each other.
2. States of Matter
- Solids: Have a definite shape, distinct boundaries, and fixed volumes.
They have negligible compressibility.
- Liquids: Have no definite shape but have a fixed volume. They take the
shape of the container.
- Gases: Have no definite shape or volume. They are highly compressible.
3. Change of State
Matter can change from one state to another by changing temperature or pressure.
- Melting Point: The temperature at which a solid melts to become a
liquid at atmospheric pressure.
- Boiling Point: The temperature at which a liquid starts boiling at
atmospheric pressure.
- Sublimation: A change of state directly from solid to gas without
changing into liquid state (e.g., Camphor).
- Latent Heat: The heat energy which has to be supplied to change the
state of a substance without raising its temperature.
4. Evaporation
The phenomenon of change of a liquid into vapours at any temperature below its boiling point
is called evaporation. Factors affecting evaporation: Surface area, Temperature, Humidity,
and Wind speed. Evaporation causes cooling.