States of matter
1.Solids
The Pull (Force): In a solid, the pull between particles is very strong. This pull holds the particles in fixed positions.
The Movement: Because the pull is so strong, particles cannot move past each other. They can only vibrate in one spot.
The Result: This is why a solid keeps a definite shape and volume.
Temperature Change: When a solid is heated, the particles vibrate faster. This pushes them slightly further apart, which causes expansion. When cooled, they vibrate less and sit closer together, causing contraction.
2. Liquids


this is a good post in my opinion