The melting point, also known as the freezing point, of a metal is the temperature at which it changes from a solid to a liquid. At the melting point, the substance is able to exist as both a solid and liquid in equilibrium.
When metals are heated, the temperature rises continually until the metal reaches the melting point. At that point the rise in temperature stops until all the solid converts into a liquid. The energy that is applied to the system at the melting point causes the phase change. The melting point is unique for each different metal and is useful for scientists attempting to identify an unknown sample of the material. In addition, each metal requires a different amount of energy for the phase change, which scientists call the latent heat of fusion.
Iron has a melting point of 1536 degrees Celsius while gold melts at 962 degrees. Mercury has a very low melting point of minus 39 degrees and is a liquid at room temperature.
When metals melt, they release the energy they absorb during the phase change. Metals with impurities and alloys often have slightly different melting and freezing points. Melting and freezing points apply to elements and compounds other than metals as well.