States of Matter & Phase Changes
📋 What it is
Solid, liquid, gas (and plasma) differ in how tightly particles are bound; heat drives changes between them.
🗣️ Coach says
The state of matter is about how much freedom the particles have. In a solid they’re locked in place (vibrating); in a liquid they slide past each other; in a gas they fly apart freely. Adding or removing heat moves a substance between these states — the same water can be ice, liquid, or steam.
🧠 Memory hook
Solid (locked) → liquid (sliding) → gas (free-flying). Heat moves matter up; cooling moves it down.
😂 Giggle
Why is entropy always increasing?
Because the universe just can't keep it together!
😲 Whoa!
Water is one of the very few substances whose SOLID form (ice) floats on its liquid — which is why ponds freeze from the top down and fish survive the winter below.
✅ Quick check: What happens to particle movement as a solid is heated into a liquid then a gas?
Say your answer out loud first — then reveal.
They move more freely — locked in a solid, sliding in a liquid, flying apart in a gas.
Adding heat increases particle freedom, changing state.
🧪 Try it! (2 minutes)
Watch an ice cube on a warm plate go solid → liquid → (eventually) vapour as heat is added.