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 Solids Type of ParticlesForces Between Particles PropertiesExamples AtomsMetallic BondSoft to hard, low to high melting point, excellent electrical and thermal conductivity, and malleable All metallic elements Ex- Al, Cu, Na, Ag, Fe Malleable- Capable of being stretched or bent into different shapes

Molecular Solids Types of ParticlesForces Between Particles PropertiesExamples Atoms or MoleculesHydrogen Bond, dipole- dipole, dispersion Soft, low to moderately high melting point, poor electrical and thermal conductivity

Ionic Solids Type of ParticlesForces Between Particles PropertiesExamples Positive and Negative ions Electrostatic InteractionsHard, brittle, high melting point, poor electrical and thermal conductivity Typical salts Ex- NaCl, KBr

Covalent-Network Solids Type of ParticlesForces Between Particles PropertiesExamples AtomsCovalent BondsVery hard, very high melting point, often poor thermal and electrical conductivity