Nature of Solids

Crystalline Solids Solid in which the representative particles exist in a highly ordered, repeating pattern.

Most solids are crystalline solids

Has a sharp melting point where it becomes a free flowing liquid

Ex. (Salt, Sugar, Snow)

Unit Cells- Representative group that is repeated throughout a crystal structure

Types of Unit Cells

Amorphous Solids Solid in which the arrangement of representative particles lacks a regular, repeating pattern.

Often referred to as supercooled liquids

When heated become softer and softer over a wide range of temperatures before it melts

Can be looked at as though the liquid was cooled to such low temperatures that it has a high viscosity and the viscosity is high enough to prevent liquid flow.

Ex. (Glass, Rubber, Plastics)

Types of Crystalline Solids

Metallic SolidsType of Particles Forces Between

ParticlesProperties Examples

Atoms Metallic Bond Soft to hard, low to high melting point, excellent electrical and thermal conductivity, and malleable

All metallic elementsEx- Al, Cu, Na, Ag, Fe

Malleable- Capable of being stretched or bent into different shapes

Molecular SolidsTypes of Particles Forces Between

ParticlesProperties Examples

Atoms or Molecules Hydrogen Bond, dipole-dipole, dispersion

Soft, low to moderately high melting point, poor electrical and thermal conductivity

Most organic compounds such as , , as well as some inorganic compounds

Ionic SolidsType of Particles Forces Between

ParticlesProperties Examples

Positive and Negative ions

Electrostatic Interactions Hard, brittle, high melting point, poor electrical and thermal conductivity

Typical saltsEx- NaCl, KBr

Covalent-Network SolidsType of Particles Forces Between

ParticlesProperties Examples

Atoms Covalent Bonds Very hard, very high melting point, often poor thermal and electrical conductivity

Diamond, C; Graphite, C; Silicon, Si; quartz, Si