mess around with this little simulation I made in 30 minutes. Explore how particles move. The temperature makes the particles move faster, and the volume is how much space they have to move around. Hold down space to combine them. Flag to reset.
The purple atoms are oxygen, while the red ones are hydrogen. Mess around with them, and here is what they would look like at: Solid- 0 temperature, 100 volume liquid- 50 temperature, 50 volume gas- 100 temperature, 0 volume.