States of Matter

PhysicsAQAGCSEUnit: Particle Model
Free taster
5 of 6 sections open
The basics

The Temperature That Refuses to Rise

📖 The Temperature That Refuses to Rise

Heat an ice cube. Its temperature rises steadily toward 0°C. Then something strange happens — you keep adding heat, but the temperature STUBBORNLY STAYS at 0°C until ALL the ice has melted. Why? Because the energy isn't making particles move faster (which would raise temperature). Instead, it's being used to break the bonds holding particles in fixed positions. Only when all bonds are broken does the temperature start rising again. Same thing happens at 100°C when water boils!
Spotlight
The Three States of Matter Compared

All matter is made of particles (atoms or molecules). The state depends on how much energy those particles have and how strongly they are attracted to each other:

Exam tip

Earn the mark scheme marks

🧠 Memory Aid

The six state changes — remember "MBSCE-D":

  • Melting (solid → liquid, energy IN)
  • Boiling/evaporation (liquid → gas, energy IN)
  • Sublimation (solid → gas, energy IN)
  • Condensation (gas → liquid, energy OUT)
  • E... wait — reverse: Freezing (liquid → solid, energy OUT)
  • Deposition (gas → solid, energy OUT)

Energy rule: Going UP the states (solid → liquid → gas) = energy IN (breaking bonds). Going DOWN (gas → liquid → solid) = energy OUT (forming bonds).

Temperature during state change: Think of a traffic jam — cars (energy) keep arriving but the queue (temperature) doesn't move until the bottleneck (bond-breaking) clears.

Now try it yourself

Quiz · Question 1 of 13

In which state of matter are particles arranged in a regular pattern and only vibrate about fixed positions?

Tap an answer to check it

This topic in real past papers

Every real exam question we've found on states of matter, with a full worked answer.

Revise every Physics topic, free during alpha

States of Matter is one of 51 topics on PrepWise — all aligned to your exam board.

Start revising free →