When we refer to water, the idea that comes to mind immediately is that of a cool, colorless liquid. When we refer to iron, we imagine a hard solid. Already the air brings us to the idea of matter in the gaseous state.
All matter that exists in nature comes in one of these forms - solid, liquid or gaseous. This is what we call the physical states of matter.
At the solid state, the water molecules are tightly "attached" to each other and move very little: they are "swaying", vibrating but not moving too far apart. It is not easy to vary the shape and volume of a solid object, such as the wood of a door or the plastic from which a pen is made, for example.
O liquid state It is intermediate between solid and gas. In it, the molecules are looser and move more than in the solid state. Bodies in the liquid state do not maintain a definite shape, but take the shape of the container containing them, as the molecules slide over each other. On the flat and horizontal surface, matter, when in liquid state, also remains in flat and horizontal form.
At the gaseous state matter is very expanded and often we cannot perceive it visually. Gaseous bodies have no volume or shape of their own and also take the shape of the container containing them. In the gaseous state, molecules move more freely than in the liquid state, are much further apart than in the solid or liquid state, and move in all directions. There are often collisions between them, which also collide with the container wall in which they are located. It's like bees trapped in a box and flying in all directions.
In short: In the solid state, water molecules vibrate at fixed positions. In the liquid state, molecules vibrate more than in the solid state, but dependent on the temperature of the liquid (the warmer, the higher the vibration, until they detach into the gas state, a phenomenon known as boiling). Consequently, in the gaseous (vapor) state the molecules vibrate strongly and in a disorderly manner.
Understand changes in physical state