Temperature plays a key role in changing the state of matter because it controls the kinetic energy of particles.
Effect of temperature on states of matter:
- Solid → Liquid (Melting)
- When a solid is heated, particles gain energy and vibrate faster.
- At the melting point, they overcome some intermolecular forces and slide past each other → becomes a liquid.
- Liquid → Gas (Evaporation/Boiling)
- Further heating increases particle motion.
- At the boiling point, particles have enough energy to break free completely → becomes a gas.
- Evaporation can also occur below boiling point from the liquid surface.
- Gas → Plasma (Ionization)
- At extremely high temperatures, gas particles gain so much energy that electrons are stripped off atoms → forms plasma (ionized gas).
- Cooling reverses the process:
- Gas → Liquid (Condensation)
- Liquid → Solid (Freezing)
- Gas → Solid (Deposition)
Key idea:
- Increasing temperature → adds energy → particles move faster → state changes from solid → liquid → gas → plasma.
- Decreasing temperature → removes energy → particles slow down → state changes from gas → liquid → solid.
In short: Temperature controls particle motion. Higher temperature makes matter change to less ordered states (solid → liquid → gas), while lower temperature makes it change to more ordered states (gas → liquid → solid).