Particles gain enough energy to overcome the forces holding them in a fixed, rigid structure, allowing them to move more freely.

Here's why:

* Melting is a phase change from solid to liquid. In solids, particles are tightly packed and vibrate in fixed positions.

* As heat is added, particles absorb energy and vibrate faster.

* When enough energy is absorbed, the vibrations become strong enough to overcome the forces holding the particles in a rigid structure. This allows them to move more freely, slipping and sliding past each other, which is characteristic of a liquid.

Let me know if you'd like more details about the specific forces involved in melting!