Why does matter contract when cooled

An exception to this is water. As water cools it contracts until it reaches the freezing point. At the freezing point water forms hexagonal crystals that take up more volume that the liquid water. At the freezing point as water becomes a solid water expands. Why do liquids contract when cooled? David Drayer. All Physics videos Unit Heat and Thermodynamics. Previous Unit Gravitation. Matt Jones.

Thank you for watching the video. Start Your Free Trial Learn more. Matt Jones M. It is the space between the particles that changes:. Remember, the particles themselves never expand. Expansion and contraction Substances expand increase in size when they get warmer, and they contract decrease in size when they get cooler. For example: Thermometers work because the liquid inside them expands and rises up the tube when it gets hotter.

There is a strong tendency to form a network of hydrogen bonds, where each hydrogen atom is in a line between two oxygen atoms. This hydrogen bonding tendency gets stronger as the temperature gets lower because there is less thermal energy to shake the hydrogen bonds out of position. Information about MathMol can be found here. In the following two pictures, the first shows a typical structure of liquid water, while the second is an ice structure; note the extra open space in the ice.