States of matter overview
1. Solid
Fixed shape and volume
Particles are tightly packed.
Strong forces hold particles together.
Particles vibrate around fixed positions.
Very difficult to compress.
2. Liquid
Fixed volume but no fixed shape.
Particles are close together.
Particles can slide past each other.
Can flow.
Difficult to compress.
3. Gas
No fixed shape or volume.
Particles are far apart.
Particles move rapidly and randomly.
Easily compressed.
Collisions with container walls create pressure.
4. Plasma
A high-energy, ionised gas.
Contains positive ions and free electrons.
Conducts electricity.
Found in stars and lightning.
5. Bose–Einstein Condensate
Forms at temperatures extremely close to absolute zero.
Particles have extremely low kinetic energy.
Quantum effects become important.
Many particles can occupy the same quantum state.
Changes of State
Endothermic — absorbs energy
Solid → Liquid: Melting
Liquid → Gas: Vaporisation
Solid → Gas: Sublimation
Gas → Plasma: Ionisation
Exothermic — releases energy
Liquid → Solid: Freezing
Gas → Liquid: Condensation
Gas → Solid: Deposition
Plasma → Gas: Recombination
Key Ideas
Higher temperature generally means greater average kinetic energy.
During a change of state, temperature can remain constant while energy changes particle arrangement and separation.
Diffusion is the net movement of particles from high concentration to low concentration.
Diffusion is generally fastest in gases.
Gas pressure is caused by particles colliding with container walls.
Non-Newtonian Fluids
Their resistance to flow changes depending on how force is applied.
Example: oobleck — it flows under slow force but becomes much more resistant to sudden force.