S Solid
- <b>Arrangement:</b> regular pattern
- <b>Spacing:</b> touching
- <b>Motion:</b> vibrating in place
- It has a definite shape because the pattern holds.
"Moving, but not going anywhere."
L Liquid
- <b>Arrangement:</b> no pattern
- <b>Spacing:</b> still touching
- <b>Motion:</b> sliding past each other
- Almost the same spacing as the solid — which is why melting expands so little.
"Close, but free to move."
G Gas
- <b>Arrangement:</b> none
- <b>Spacing:</b> about ten times further apart
- <b>Motion:</b> fast, straight, until they hit something
- About a thousand times the volume of the liquid.
"Far apart and fast."
✗ What the model forbids
- Particles do <b>not</b> get bigger when heated.
- A single particle cannot <b>melt</b>.
- There is <b>nothing</b> in the spaces — not air.
- Heating creates no new particles.
"Only the spacing and the speed change."