Liquids and Solids

Solids

Objectives1. Explain the properties of solids according to the

KMT.

2. Distinguish between amorphous and crystalline solids.

3. Define crystal structure and unit cell.

Solids

• Definite shape• Definite volume• Intermolecular forces

have a large effect; particles are held in fixed positions

Properties of SolidsDefinite melting point• Temperature at which the particles of a solid

overcome intermolecular forces that hold them in fixed positions

• Freezing points and melting points have the same values

• Amorphous do not have a definite melting point.

Properties of SolidsHigh Density• Particles of solid are packed close together as a result

of low K.E. and high intermolecular forces.

Incompressibility• Particles cannot be pressed into a smaller volume.

Low Rate of Diffusion• Result of limited particle movement and limited

space between particles

Crystalline Solids• Solids in which the

particles are arranged in an orderly geometric pattern

• Arrangement of particles is called a crystal lattice

• The simplest portion of the lattice is called the unit cell

Types of Crystalline SolidsIonic • Ionic bonds between anions and cations

Covalent Network• Covalent bonds between atoms.• Examples: Diamond (Cx), quartz (SiO2)x,

Metallic• Metal cations surrounded by a see of electrons

Molecular covalent• Molecules held together by intermolecular forces

(disperson, dipole-dipole, hydrogen bonding

Types of Crystalline Solids

Amorphous Solids• Particles are arranged

randomly• Sometimes referred to

as supercooled liquids• Examples include glass,

rubber, plastics.