Entropy

[Tara_Hekmati_3B]

Why is it that at 0 K the entropy of a crystal becomes zero? What does this temperature have to do with the crystals structure?

[Eljie_2F]

The definition of temperature is the amount of movement in temperature. 0 kelvin is defined as the point at which there is no movement in the atoms of the object being observed. Hypothetically, if a perfect crystal were to reach this temperature its entropy would reach zero because there would be no movement. With no movement, the crystal can not reposition itself, leading to an entropy of zero. Regarding the crystal's structure, it means that there is only one configuration in which the crystal at 0 K can exist in.