Thermal expansion and contraction

Let’s think about the different chronological states of matter. The idea behind thermal expansion is that gases expand as the temperature increases. Let’s use a balloon to help illustrate or somewhat visualize the concept. So if you have a balloon and you heat up the contents, the balloon will get larger. Solids expand and contract the least of all the states of matter. The opposite of expansion is contraction. If things expand with the addition of heat, it makes sense that they contract when heat is removed. If you remove enough heat from a gas it will become a liquid. Liquids can turn into solids with further cooling. What happens when you remove almost all of the energy from a system? Scientists use the terms absolute zero to describe a system that has no kinetic energy. In conclusion we can then say that when there is no kinetic energy in a system, all molecular motion stops. It seems that even the atoms begin to merge at these low temperatures.

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