From Solid to Plasma: The Fourth State of Matter

Adding energy walks a material up the four states. Drag the energy slider from a cold solid, through liquid and gas, until collisions strip electrons from atoms and the gas ionizes into plasma — a soup of free electrons and ions.

Solid
Animation of particles moving from a fixed solid lattice, to a flowing liquid, to a dispersed gas, and finally ionizing into a plasma of free electrons and positive ions as the energy input rises.
State
Solid
Ionization (schematic)
0%
Net charge
neutral
The physics. The states are set by the competition between particle kinetic energy and the bonds holding particles in place. Melting and boiling free the atoms; ionization is different in kind — enough energy strips electrons from atoms entirely, leaving free charges that conduct current and respond to fields. A plasma stays quasi‑neutral: electrons and ions are separately free, but their charges balance over any meaningful volume, so the net charge readout stays near zero throughout. Real laboratory cold plasmas are usually only weakly ionized — only a small fraction of atoms is ionized at any moment — so the fully ionized end of this slider is a schematic extreme, not the typical operating point. This is a schematic teaching model, not a molecular-dynamics simulation.