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How does particle motion change when a gas cools into a liquid?

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Diagram showing four physical states of matter: solid with tightly packed molecules, liquid with loosely packed molecules, gas with widely spaced molecules, and plasma with free electrons and nuclei, each labeled with descriptions and an arrow indicating increasing energy. — phase States of matter.

When a gas cools into a liquid, the motion of its constituent particles changes significantly as they transition from a state of high-speed, independent movement to a more cohesive state.

In a gaseous state, particles move fast enough to overcome the influence of intermolecular forces, traveling in straight lines and colliding without losing energy. As the gas cools, the average kinetic energy of these particles decreases. When particles slow down sufficiently to linger near one another, the force of attraction—such as van der Waals forces—overcomes their reduced kinetic energy, causing them to coalesce into a liquid.12

During this process, known as condensation, each particle releases a measure of energy called the latent heat of liquefaction. Once in the liquid state, the particles continue to move, but their range of motion is restricted; they typically travel distances on the order of molecular diameters before colliding with other particles.1