(CHEM) L1 Kinetic Molecular Theory

• Kinetic Molecular Theory is a model used to explain the behavior of matter.
• Kinetic Molecular Theory of Gases describes gases as atoms or molecules that move in random, ceaseless motion.
• Gases are characterized by having no definite volume, i.e., they can be expanded or compressed.
• Condensation (Gas to Liquid) occurs when a gas is cooled and/or compressed to a smaller volume, gas molecules have limited motion.
• Since gas molecules become “crowded”, attractive forces between them become significant.
• When the strength of attractive forces exceeds the kinetic energy, the gas turns into a liquid.
• The attractive forces in liquid hold molecules together, causing liquids to have definite volume.
• Liquids are almost incompressible because of the close distance between molecules.
• Liquids can still move past each other, enabling them to conform with the shape of the container they occupy.
• Since molecules in liquid are more compact than those in gases, liquids have higher densities compared to gas.
• Freezing (Liquid to Solid) occurs when a liquid is brought to low temperature, the kinetic energy also decreases, making the molecules to almost stay in place and make vibrations in position.
• Unlike liquids and gases that are fluid, solids are rigid because of the very compact and highly ordered arrangement of molecules.
• Solids have greater densities than Liquid.
• Phase is matter having a uniform composition and appearance.
• Condensed Phases (Liquids and Solids) have molecules closer to each other compared to gases.
• Kinetic Molecular Model of Liquids and Solids emphasizes the proximity of molecules and the strength of attractive forces among them, which render their distinct properties.
• Matter is made up of particles that are constantly in motion.
• The amount of kinetic energy is related to its temperature.
• The amount of space in between particles is related to the substance’s state of matter.
• Phase Changes happen when the temperature of the substance changes sufficiently.