Describe what happens to the arrangment and average kinetic energy of water molecules as they freeze.

All particles have energy, and the energy varies depending on the temperature the sample of matter is in, which determines if the substance is a solid, liquid, or gas. Solid particles have the least amount of energy, and gas particles have the greatest amount of energy.

The temperature of a substance is a measure of the average kinetic energy of the particles. A change in phase may occur when the energy of the particles is changed.

There are spaces between particles of matter. The average amount of empty space between molecules gets progressively larger as a sample of matter moves from the solid to the liquid and gas phases.

Key Terms

kinetic molecular theory: Theory of treating samples of matter as a large number of small particles (atoms or molecules), all of which are in constant, random motion

kinetic: Of or relating to motion.

lattice: A regular spacing or arrangement of atoms/molecules within a crystal.

phase: A component in a material system that is distinguished by chemical composition and/or physical state. Matter can exist in the solid, liquid, and gaseous phases.