States of matter
Heat an element and watch it change state — or skip a state entirely.
Scientific learning path
- 01UnderstandLive
- 02ExploreLive
- 03ExperimentLive
- 04ObserveLive
- 05ExplainLive
- 06ApplyLive
- 07TestBuilding
How the particles sit
All figures at one atmosphere
Description of this simulation
At 589 K and one atmosphere, Arsenic is a solid. Arsenic has no liquid state at this pressure at all: its solid turns straight to vapour at 887 K, below the 1090 K it would need to melt. That is sublimation, and it is why the two numbers look the wrong way round.
State at this temperature
Solid
Fixed neighbours in a lattice, vibrating in place. A solid keeps its shape.
- Sublimes at
- 887 K614 °C
- Liquid over
- No liquid state at this pressure
Sublimation
The boiling point of this element is below its melting point, which is not an error. Its solid reaches a vapour pressure of one atmosphere before it gets hot enough to melt, so at this pressure it turns straight to vapour and has no liquid state at all.
Why there is no pressure control
A phase diagram needs a vapour-pressure curve for every substance on it. The reference set carries melting and boiling points at one atmosphere only, so a pressure axis would mean drawing a boundary nobody measured. It is left out rather than invented.
What this model shows — and what it simplifies
Educational ModelMelting and boiling points are the published values at one atmosphere, and the state at any temperature is read off them rather than modelled.
Where do we see this in real life?
Dry ice sublimes rather than melting, which is why it leaves no puddle. Freeze-drying uses the same trick on food, and tungsten is chosen for furnace parts and lamp filaments because it stays solid to 3695 K.