Matter in Our Surroundings - Chapter Notes
Easy original notes on states of matter, change of state, evaporation and latent heat for Class 9 Science.
States of matter
Matter is anything that has mass and occupies space. It exists mainly as solid, liquid and gas.
- Solid: fixed shape and volume; particles are packed closely.
- Liquid: fixed volume, no fixed shape; particles can slide past each other.
- Gas: no fixed shape or volume; particles move freely with large gaps.
Change of state
- Melting: solid to liquid at the melting point.
- Boiling: liquid to gas at the boiling point (water: 100 degrees C at normal pressure).
- Sublimation: solid directly to gas, for example camphor.
Evaporation
Evaporation happens at any temperature, only at the surface, and causes cooling. It increases with higher temperature, larger surface area, lower humidity and wind.
Quick revision
- Heating raises particle energy; cooling lowers it.
- Latent heat is the heat absorbed or released during a change of state without any change in temperature.