Answer:
They gain kinetic energy
Step-by-step explanation:
When the temperature of the particles in a substance rise, its internal energy increases. This internal energy is thus translated to kinetic energy of the particles in the substance. If the substance is a solid, as the kinetic energy increases, the vibrations of the particles of the substance increases causing it to undergo a change of state to liquid when the temperature reaches its melting point.
This change of state also occurs from the liquid state to the gaseous state as the internal energy of the substance, and thus the kinetic energy of the particles increase when the temperature reaches the substance's boiling point.
So, as the temperature of a substance rises, the particles of the substance gain kinetic energy.