States of Matter & Phase Changes
📋 What it is
Solid, liquid, gas — the same stuff, just how tightly its particles are packed and moving.
🗣️ Coach says
Ice, water, steam are all H₂O — the difference is how the particles behave. In a solid they’re locked in place; in a liquid they slide past each other; in a gas they zoom around freely. Add heat and they speed up and spread out; remove heat and they slow and pack in.
🧠 Memory hook
Solid = locked, liquid = sliding, gas = zooming. Heat spreads them out.
😂 Giggle
What did the scientist say when she found two isotopes of helium?
HeHe!
😲 Whoa!
Water is one of the very few substances that EXPANDS when it freezes — that’s why ice floats and why water pipes burst in winter.
✅ Quick check: When ice melts into water, is it a new substance?
Say your answer out loud first — then reveal.
No — it’s the SAME substance (H₂O); only the state changed as the particles gained energy and spread out.
Phase changes rearrange particles but don’t change the substance itself.
🪄 Trick question: Does a gas weigh nothing because it floats away?
Careful — think it through, then reveal.
No — gases still have mass; a balloon of gas weighs more than an empty one, it just spreads out so it feels light.
All states of matter, including gases, have mass.
🧪 Try it! (2 minutes)
Watch an ice cube melt in your hand. The particles are gaining heat energy and loosening from solid to liquid.