- The unit cells that makes up the entire crystalline solid has a fixed value for the length of the edges and the angle between the edges.

- Therefore, the heat energy required to melt a crystalline solid would have a fixed value.
- The energy required to bring about the change of state from a unit mass of the solid to the liquid is called the heat of fusion, and the temperature at which it happens is called the melting point.

Related Reading- Heat of Fusion and Melting Point- Crystalline versus Amorphous Solids
