States of Matter Changes 1 October 01, 2018 Melting: From Solid to Liquid Melting: change from solid to liquid Melting Point: temperature at which solid melts Increase thermal energy (endothermic Ex. Melting point of pure water is 0 o C. change) Thermal energy makes water molecules vibrate faster, raising their temperature. At melting point, solid particles vibrate so fast they break free from their fixed positions. Freezing: change from liquid to solid Freezing Point: temperature at which liquid freezes Freezing: From Liquid to Solid Particles are moving so slowly they form regular patterns. decrease in thermal energy (exothermic change) Vaporization: From Liquid to Gas Vaporization: change from a liquid to a gas Boiling Point: temperature at which liquid turns to gas ***Note: Evaporation can occur at surface of (Ex. Eventually a cup of water will evaporate liquid without heating liquid*** if left unattended; puddle of water after it rained) Evaporation is the process when vaporization takes place. Condensation: From Gas to Liquid Condensation: change from a gas to a liquid Occurs when particles in a gas lose thermal energy to form a liquid (exothermic change). Ex. Clouds form when water vapor in atmosphere condenses into liquid droplets (rain) Bathroom mirror Sweat on a bottle Review