
# 12: Liquids, Solids, and Intermolecular Forces


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In Chapter 6, we discussed the properties of gases. Here, we consider some properties of liquids and solids. As a review, the Table below lists some general properties of the three phases of matter.

Phase Shape Density Compressibility
Gas fills entire container low high
Liquid fills a container from bottom to top high low
Solid rigid high low

• 12.1: Interactions between Molecules
All substances experience dispersion forces between their particles. Substances that are polar experience dipole-dipole interactions. Substances with covalent bonds between an H atom and N, O, or F atoms experience hydrogen bonding. The preferred phase of a substance depends on the strength of the intermolecular force and the energy of the particles.
• 12.2: Properties of Liquids and Solids
All liquids evaporate. If volume is limited, evaporation eventually reaches a dynamic equilibrium, and a constant vapor pressure is maintained. All liquids experience surface tension, an imbalance of forces at the surface of the liquid. All liquids experience capillary action, demonstrating either capillary rise or capillary depression in the presence of other substances. Solids can be divided into amorphous solids and crystalline solids.
• 12.3: Intermolecular Forces in Action - Surface Tension and Viscosity
The surface tension of a liquid is a measure of the elastic force in the liquid's surface. Liquids with strong intermolecular forces have higher surface tensions than liquids with weaker forces.
• 12.4: Evaporation and Condensation
Evaporation is the conversion of a liquid to its vapor below the boiling temperature of the liquid. Condensation is the change of state from a gas to a liquid. As the temperature increases, the rate of evaporation increases.
• 12.5: Melting, Freezing, and Sublimation
Phase changes can occur between any two phases of matter. All phase changes occur with a simultaneous change in energy. All phase changes are isothermal.
• 12.6: Types of Intermolecular Forces: Dispersion, Dipole–Dipole, Hydrogen Bonding, and Ion-Dipole
Covalent bonds between atoms that are not identical will produce polar bonds. Molecules with polar bonds and non-symmetrical shapes will have a dipole. Hydrogen bonding is a special interaction felt between molecules, which is a stronger interaction than polar-polar attraction. Hydrogen bonding occurs between molecules in which a hydrogen atom is bonded to a very electronegative fluorine, oxygen, or nitrogen atom.
• 12.7: Types of Crystalline Solids: Molecular, Ionic, and Atomic
Crystalline substances can be described by the types of particles in them and the types of chemical bonding that takes place between the particles. There are four types of crystals: (1) ionic, (2) metallic, (3) covalent network, and (4) molecular.
• 12.8: Water - A Remarkable Molecule
Water has several properties that make it a unique substance among substances. It is an excellent solvent; it dissolves many other substances and allows those substances to react when in solution. In fact, water is sometimes called the universal solvent because of this ability. Water has unusually high melting and boiling points. Unlike most substances, the solid form of water is less dense than its liquid form, which allows ice to float on water.