What is the term for the heat energy required to change a substance from solid to liquid at its melting point?

The heat energy required to change a substance from solid to liquid at its melting point is referred to as the heat of fusion. This term specifically defines the energy needed to overcome the forces holding the particles in a solid state, allowing them to move freely and enter the liquid state. The process occurs at a constant temperature, which is characteristic of phase changes, ensuring that all the energy input goes into breaking the intermolecular bonds rather than increasing the temperature of the substance.

In the context of the other options, heat of vaporization refers to the energy required to convert a liquid into a gas, specific heat capacity is the amount of heat required to raise the temperature of a unit mass of a substance by one degree Celsius, and latent heat is a broader term that can refer to energy absorbed or released during a phase change without changing temperature, encompassing both melting and vaporization. However, for the specific transition from solid to liquid, the precise term is heat of fusion.