This program scrutinizes the concept of phase transitions—from naturally occurring changes in state to those created in laboratories—in five sections: Solids, Liquids, and Gases (properties of molecules in different states; hydrogen bonds, dipole-dipole forces, dispersion forces; effects of temperature, pressure, and volume on atomic and molecular movement; Ideal Gas Law); Evaporation and Condensation (intermolecular forces, boiling/condensing point, endothermic reactions); Melting and Freezing (melting/freezing point, ionic and covalent bonds, cations and anions); Sublimation and Deposition (triple points and phase diagrams); and Other States of Matter (plasma, liquid crystals, Bose-Einstein condensates, superfluids and supersolids). A viewable/printable instructor’s guide is available online. A Films for the Humanities & Sciences Production. A part of the series Essential Chemistry. (22 minutes)