Unlike solid and liquid state, molecules in gaseous state show random motion. That is the reason, gases take the shape of container and spread quickly in space. The random motion of molecules in the gaseous state is due to high kinetic energy in molecules. They have weak intermolecular interactions between them. The intermolecular space between gaseous molecules is very large. They can show all the three types of molecular motion, vibrational, rotational and translational motion. In vibrational motion, molecules move back and forth whereas in rotational motion the molecule rotates in space. In translational motion molecules move in certain directions. Molecules of solid-state are capable of vibrational motion due to strong intermolecular forces. Therefore, they show least random molecular motions. Like solids, liquids are capable of vibrational motion but at the same time they can also show rotational and translational motions due to weak intermolecular forces between molecules. Hence, liquids can show random molecular motions but less random compared to gas molecules. So we can say that random motion is related to temperatures, intermolecular forces of attractions, the kinetic energy of molecules and heat transfer.
