Physics * » Molecules*
The molecules are formed of two or several expanding atoms.
The atoms of the molecules open up expanding molecule´s common energywaves.
In liquids these waves are directed partly beyond the centres of molecules nextby. Between the molecules of the liquid there moves energy for a longer time than in solid substances. This is why often into the molecule of the liquid there comes a larger amount of energy from another direction. With this energy the molecule moves a long journey between the other expanding molecules towards another direction.
Between the molecules of the gases the energy, that comes from the atomcores of the gas, moves even longer journeys. Now there comes relatively even more energy towards the centres of the gas molecules from another direction. That is why the gas molecules are thrown even longer distance between other molecules.