# Basic Chemistry/States of matter

Matter exists in four different forms - solid, liquid, gas, and plasma. These are the four states of matter. You can recognize each state because they have different properties. A property of a material describes how it behaves. This behavior is not observable at the chemical level due to microscopic sized particles. We can observe how many H2O particles behave when we open a faucet, releasing water, which is a lot of H2O particles in their liquid state. Of course we can observe other states of H2O particle groupings, at low temperatures they freeze, demonstrating a solid property. At high temperatures they form a gas called steam.

## Readings

* Wikipedia: State of matter
* Wikipedia: Solid
* Wikipedia: Liquid
* Wikipedia: Gas

## States of matter

| Property | Solids | Liquids | Gases |
| Volume | has definite volume | has definite volume | has no definite volume-always fills the container they are in |
| Shape | have a definite shape | match the shape of the container | become the same shape as the container |
| Density | have a high density | have a high density | have a low density |
| Compressibility | not easily squashed | not easily squashed | easily squashed |
| Flow | don't flow | flow easily | flow easily |

## Particle theory

* All materials are made up of particles.
* The particles that are in a substance (material) stay the same whatever state the substance is in. The only thing that changes is the arrangement of the particles and the energy they have.
* Whichever state the substance is in depends on how strongly the particles stick together. And how well the particles stick together depends on:
** the material
** the temperature
** the pressure.
* This is particle theory, and it explains all the different properties of solids, liquids and gases.

### Solids

* PARTICLES ARE HELD VERY CLOSE TOGETHER AND HAVE LIMITED MOVEMENT SPACE
* They are held tightly together by strong forces of attraction.
* They are held in fixed positions but they do vibrate.
* Because the particles don't move, solids have a definite shape and volume, and can't flow.
* Because the particles are already packed closely together, solids can't easily be compressed.
* Because there are lots of particles in a small volume, solids are dense.
* Powdered solids cannot take the shape of their container.

### Liquids

* PARTICLES ARE CLOSE TOGETHER BUT CAN MOVE
* Particles are still touching and held by very strong forces of attraction.
* They are free to move past each other.
* Because the particles can move, liquids don't have a definite shape, and they can flow.
* Because the particles are still packed close together, liquids can't easily be compressed and keep the same volume.
* Because there are lots of particles in a small volume, liquids have almost the same density as when they are solid. Some, like water are actually more dense than their solid, but most are very slightly less dense.

### Gases

* PARTICLES ARE FAR APART
* Particles are far apart from each other because there are very weak forces of attraction between them.
* They move fast in all directions.
* Because of this, gases don't have a definite shape or volume and fill any container.
* Because there is lots of free space between particles, gases can easily be compressed.
* Because there aren't many particles in a large volume, gases have very low densities typically 1000 times less than in their condensed state as solid or liquid at atmospheric temperature and pressure.