Solids and the Kinetic Molecular Theory Ryan Rowland AJ Rosciszewski David Milostan Toni Lukic Allison Koch
Vocabulary • Crystalline Solids: Solids consisting of solids • Crystals: a substance in which the particles are arranged in an orderly, geometric, repeating pattern. • Amorphous Solids: solid in which the particles are arranged randomly • Melting: physical change of a solid to a liquid by the addition of energy as heat • Melting Point: the temperature at which a solid becomes a liquid • Super cooled Liquids: substances that retain certain liquids properties even at temperatures at which they appear to be solid • Crystal Structure: total three dimensional arrangement of particles of a crystal
Types of Solids • Amorphous Solids: • Particles are not arranged in a regular pattern. • Crystalline Solids: • Exist as single crystals, or groups of crystals fused together. • Crystal structure, and crystal lattice.
Crystalline Systems • Cubic • Tetragonal • Hexagonal • Trigonal • Orthorhombic • Monoclinic • Triclinic
Characteristics of Solids • Definite shape and volume: • Solids maintain a definite shape without a container. Solids have a definite volume because their particles are packed tightly together. • Definite melting point: • At melting point, kinetic energies of the particles over come the attractive forces holding them together. • High density and incompressibility: • Substances are most dense in the solid state. For practical purposes, solids can be considered incompressible. • Low rate of diffusion: • Rate of diffusion is millions of times slower in solids.
Products of Binding Forces in Crystals • Ionic Crystals: • NaCl, MgF2 • Covalent Network Crystals: • (SiO2)x, Cx (Diamond) • Metallic Crystals: • Hg, Cu, Fe, W • Covalent Molecular Crystals: • Nonpolar: H2, O2, CH4, CCl4, C6H6 • Polar: NH3, H2O
Understand • Ionic or network covalent substances have stronger forces and are not as likely to volatilize. • These substances often have little if any color.