8.1: Introduction to Gases 8.2: Gas Pressure 8.3: Relating Pressure, Volume, Amount, and Temperature- The Ideal Gas Law 8.4: Stoichiometry of Gaseous Substances, Mixtures, and Reactions 8.5: Effusion and Diffusion of Gases 8.6: The Kinetic-Molecular Theory 8.7: Non-Ideal Gas Behavior 8.8: Videos- Gases 8.9: Assignment—Gases Thumbnail: Motion of gas molecules. The randomized thermal vibrations of fundamental particles such as atoms and molecules—gives a substance its “kinetic temperature.” Here, the size of helium atoms relative to their spacing is shown to scale under 1950 atmospheres of pressure. (CC BY-SA 3.0; Greg L ).