Solids, Liquids and Gases
Matter and Its States
- Matter is anything that occupies space and has mass, comprised of tiny particles called atoms.
- Atoms can exist freely, or they can combine to form molecules.
- Matter can mainly be in three states: solid, liquid, or gas.
- The state of matter depends on how the atoms or molecules are arranged and the energy they possess.
Solids
- In solids, the particles are tightly packed together in a fixed, regular arrangement.
- The particles in a solid vibrate in place but don't move from their fixed positions β this makes solids maintain a fixed shape and volume.
- Solids have the strongest intermolecular forces.
- Solids do not flow and are not generally compressible.
Liquids
- In liquids, particles are in a random arrangement but are still close together.
- The particles in a liquid can move around each other but are still in close contact; this allows a liquid to flow and take the shape of its container.
- Liquids have medium strength intermolecular forces.
- Although liquids can be slightly compressed, they are mostly incompressible.
Gases
- In gases, the particles are well separated and in a completely random arrangement.
- The particles in a gas move quickly in all directions and have complete freedom of movement; this allows a gas to fill any given space.
- Gases have the weakest intermolecular forces.
- Gases are highly compressible and always expand to fill their containers.
Changing States
- Melting, freezing, evaporation, and condensation are the processes of state changes.
- When a solid is heated, it will melt into a liquid at its melting point.
- When a liquid is cooled, it will freeze into a solid at its freezing point.
- When a liquid is heated, it will evaporate into a gas at its boiling point.
- When a gas is cooled, it will condense into a liquid at its condensation point.
The Kinetic Theory of Matter
- The Kinetic Theory of matter states that all particles of matter are in constant motion and this motion has consequences that can be studied on a macroscopic level (what we can see) and microscopic (what we cannot see but can imagine or model).
- Increasing the temperature of a substance increases the kinetic energy of its particles, making them move more rapidly and irregularly.
- The kinetic energy of particles and the attractive forces between particles are what determine the state of the substance - solid, liquid, or gas.