Ice, Water, Steam

Ice, water, steam — the same molecules

Pick a tool and hold it on the glass. Watch both views at once: the glass as you would see it, and the water molecules themselves.

In the glasswhat you can see

hold on the glass

Flame — heat straight through the glass.

Zoomed inthe molecules themselves

click a molecule to follow it

Heat energyDrag it yourself, or let a tool move it

LiquidWater. The molecules still cling to each other, but they slide past and swap places.

20 °C68 °F

Moderatemolecule speed

Oxygen. The big atom at the middle of every water molecule.
Hydrogen. The two small ones. They sit at an angle, which is why ice builds six-sided rings.
Hydrogen bonds. The faint links between molecules. Weak enough that heat breaks them, strong enough to build ice.
Your molecule. Click one in the zoomed view and the camera keeps it centred wherever it goes.
Steam. Molecules that have torn loose from the liquid altogether.

In all three states this is the same molecule — one oxygen atom with two hydrogens. What changes is how much energy it has. Cold molecules have so little that the weak bonds between them hold everything in a rigid lattice, and that is ice. Add heat and they break out of their fixed places but still cling to each other and slide past, and that is liquid water. Add more and they tear loose completely and fly apart as vapour you cannot see. Watch the thermometer while ice is melting or water is boiling: it stops rising, because every bit of heat you add is going into breaking bonds instead of into speed. The fan shows the other way out — molecules leaving the surface one at a time, at any temperature, with no boiling needed. The same steps run backwards in the sky: vapour rising off a warm river cools, gathers into cloud droplets and falls again as rain or snow. The water cycle is this animation at the size of a watershed.