What happens to the particles in a substance at its melting point?

At the melting point of a substance, the particles gain kinetic energy, which is crucial for the phase transition from solid to liquid. As the temperature reaches the melting point, the energy supplied causes the particles to vibrate more vigorously. This increased movement overcomes the forces that hold the particles in a fixed position within the solid structure, allowing them to break free from their rigid arrangement. Consequently, the arrangement of the particles transforms as they transition into a liquid state, where they can move more freely.

In this context, the other options do not accurately describe the behavior of particles at the melting point. For instance, solidifying occurs at the freezing point, not during melting. Moving closer together does not happen; rather, the particles actually move apart as they transition into the liquid phase. Lastly, separating into individual atoms is not characteristic of melting, as melting involves the movement of molecules rather than their breakdown into atomic components. Thus, the correct answer emphasizes the energy gain and transformation from solid to liquid, making it a fundamental concept in understanding phase changes.