Particle theory
Definition
Particle theory explains that all matter is made up of extremely tiny particles. These particles are too small to be seen with our eyes. They are always moving, have spaces between them, and attract each other. The way these particles move and are arranged decides whether a substance is a solid, liquid, or gas.
Examples
1. Perfume spreading in a room
When perfume is sprayed, its particles move through the air and spread everywhere. This shows that particles are always moving.
2. Ice melting into water
When ice is heated, its particles gain energy, move faster, and change from a solid to a liquid.
3. Sugar dissolving in water
Sugar seems to disappear, but its particles mix with water particles and spread evenly.
Main Details
All matter is made of tiny particles.
Particles are always in motion, even in solids.
There is space between particles.
Particles attract each other.
Heating increases particle movement.
Cooling slows down particle movement.
Solids have tightly packed particles.
Fun Fact
Even though solids look hard and still, their particles are vibrating continuously, which means nothing in the world is truly at rest.