Phase Changes

phase changes occur when matter changes from one state to another due to the addition or removal of energy. these changes affect how particles move, but they do not change the chemical identity of the substance.

common phase changes

• melting: solid → liquid
• freezing: liquid → solid
• evaporation: liquid → gas
• condensation: gas → liquid
• sublimation: solid → gas
• deposition: gas → solid
• ionization: gas → plasma
• recombination: plasma → gas

energy and particles

when energy is added, particles move faster and spread farther apart. when energy is removed, particles slow down and move closer together. this change in particle motion is what causes phase changes.

real-world examples

• ice melting into water on a warm day
• water vapor condensing on a cold mirror
• dry ice sublimating into carbon dioxide gas
• lightning creating plasma in the atmosphere