Solids, Liquids & Gases
- The three states of matter are solid, liquid and gas
- The kinetic theory of matter is a model that attempts to explain the properties of the three states of matter
- In this model, particles are assumed to be small spheres
Water as a solid, liquid, and a gas
Water has three states of matter; solid ice, liquid water and gaseous steam. The difference between each state is the arrangement of the particles
Solids
- Particles in a solid...
- Are closely packed
- Are arranged in a fixed pattern (lattice structure)
- Can only vibrate about their fixed positions
- Have low energies compared to particles in liquids and gases
- Therefore, do not have enough energy to overcome the intermolecular forces of attraction holding them together
Molecular arrangement in a solid
In a solid, particles are arranged in a fixed pattern, with no spaces between them, and are only able to vibrate about their fixed positions
- As a result of the arrangement and behaviour of their particles, solids...
- Have a fixed shape (although some solids can be deformed when forces are applied)
- Have a fixed volume
- Are very difficult to compress
- Have higher densities than liquids and gases
Liquids
- Particles in a liquid...
- Are closely packed
- Are randomly arranged (i.e. there is no fixed pattern)
- Can flow past each other
- Have higher energies than particles in solids, but lower energies than gas particles
- Therefore, have enough energy to partially overcome the intermolecular forces of attraction holding them together
Molecular arrangement in a liquid
In a liquid, particles are arranged randomly and are able to flow past one another
- As a result of the arrangement and behaviour of their particles, liquids...
- Do not have a fixed shape and take the shape of the container they are held in
- Have a fixed volume
- Are difficult to compress
- Have lower densities than solids, but higher densities than gases
Gases
- Particles in a gas...
- Are far apart (the average distance between the particles is ∼10 times greater than the distance between the particles in solids and liquids)
- Are randomly arranged
- Move around in all directions at a variety of speeds, occasionally colliding with each other and with the walls of the container they are in
- Are negligible in size compared to the volume occupied by the gas
- Have higher energies than particles in solids and liquids
- Therefore, have enough energy to overcome the intermolecular forces of attraction holding them together
Molecular arrangement in a gas
In a gas, particles can move around freely in all directions (shown by the arrows)
- As a result of the arrangement and behaviour of their particles, gases...
- Do not have a fixed shape and take the shape of the container they are held in
- Do not have a fixed volume and expand to completely fill the available volume
- Can be compressed
- Have the lowest densities (∼1000 times smaller than the densities of solids and liquids)
| State of Matter | Solid | Liquid | Gas |
| Particle arrangement | Fixed pattern (lattice structure) | Random | Random |
| Space between particles | No space | Some space | Large space |
| Particle movement | Vibrates around a fixed position | Flows past each other | Moves around at different speeds |
| Particle energy | Low | Medium | High |
| Substance shape | Fixed | Not fixed | Not fixed |
| Substance volume | Fixed | Fixed | Not fixed |
| Substance density | High | Medium | Low |
| 2D diagram of particle arrangement |  |
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