How do particle dynamics change during phase transitions?

During phase transitions, particle dynamics change in terms of energy, movement, and arrangement.

Phase transitions refer to the transformation of matter from one state to another, such as from solid to liquid (melting), liquid to gas (evaporation), or the reverse processes. These transitions are driven by changes in temperature or pressure, which directly affect the energy and behaviour of the particles involved.

In a solid, particles are closely packed in a fixed, regular pattern and vibrate about fixed positions. They have low kinetic energy. As the solid is heated, the particles gain energy, causing them to vibrate more vigorously. This weakens the forces of attraction between them. During the phase transition from solid to liquid, known as melting, the particles gain enough energy to break free from their fixed positions. They start to move more freely, sliding past each other, which is characteristic of liquids.

In the transition from liquid to gas (evaporation), the particles continue to gain energy from the heat. This increased energy allows them to overcome the attractive forces between them completely. The particles move independently and are far apart, which is characteristic of gases.

In reverse transitions, such as condensation (gas to liquid) or freezing (liquid to solid), the particles lose energy. This loss of energy reduces their movement, allowing the attractive forces to pull them closer together. In freezing, the particles slow down enough to adopt fixed positions, forming a solid.

In summary, during phase transitions, the dynamics of particles change significantly. The energy, movement, and arrangement of particles are all affected, leading to different states of matter. Understanding these changes is crucial to understanding the fundamental behaviour of matter in different conditions.