CHE 101 Lecture Notes - Lecture 13: Intermolecular Force, Hydrogen Bond, Chemical Polarity
Document Summary
Chapter 11: intermolecular forces, phase changes and phase diagrams. These forces govern whether it is a solid, liquid, or gas: intermolecular forces. Intermolecular forces describe the attractive interactions between molecules. The strength of the intermolecular forces governs whether a substance is a gas, liquid, or solid. Strong forces ionic, covalent (observed in solids) Intermediate hydrogen bonding, dipole-dipole (observed in liquids) Solid: ordered arrangement, particles in fixed positions that are close together. Liquids: disorder, particle/clusters are free to move relative to each other, fairly close together. Gas: total disorder, particles have complete freedom of motion, particles are far apart. Dipole- dipole forces, figure 11. 7 ****polar molecules (also called van der waals) Dipole- dipole interactions exist for molecules that have molecular dipoles. Hydrogen bonding is a type of dipole-dipole that involves a polar bond to hydrogen. Hydrogen bonds are usually the stronger than other dipole-dipole. H f h f h f. The unique properties of water arise from hydrogen bonding.