When a liquid boils, what primarily happens to its particles?

When a liquid boils, the primary process that occurs is the breaking of intermolecular bonds between the particles. In a liquid, the particles are held together by these bonds, but as the temperature rises, they gain kinetic energy. When the liquid reaches its boiling point, this energy is sufficient to overcome the attractive forces between the particles. This allows the particles to move freely and transition into the gas phase.

The process of boiling is characterized by the transformation of the liquid into vapor. The energy involved in this transformation is known as latent heat. This energy is absorbed by the liquid during boiling while the temperature remains constant, enabling the particles to escape from the liquid state.

In contrast, the other options do not accurately represent what occurs during boiling. The particles do not settle at the bottom; they are indeed in constant motion. Condensation into a solid is not applicable to boiling, as this process involves a transition typically associated with cooling rather than heating. Lastly, while heat absorption does occur during boiling, it is not a slow process and is specifically associated with overcoming intermolecular forces rather than a gradual accumulation of heat.