Solids Chapter 10 Section 3

Properties of Solids and the Kinetic-Molecular Theory Particles of a solid are even closer together than a liquid. Intermolecular forces are much more effective because of proximity. These forces keep the particles in a solid in relatively fixed positions, with only vibrational movement around fixed points.

Types of Solids Crystalline solids: consist of crystal structure Crystal: a substance in which the particles are arranged in an orderly, geometric, repeating pattern Amorphous solid: the particles are arranged randomly, like glass and plastics

 

Crystalline Solids Crystal structure: 3-D arrangement of particles of a crystal Lattice: the coordinate system that represents a crystal structure The crystal will have one of seven types of symmetry

Seven types of crystalline systems

Definite Shape and Volume Solids maintain a definite shape The volume of a solid changes only minimally with a change in temperature or pressure The particles are so close together, that it is hard to compress them further

Compressibility Solids are generally less compressible than liquids. They are usually considered to be incompressible.

Definite Melting Point Melting: the physical change of a solid to a liquid by the addition of energy, usually as heat Melting point: the temperature at which a solid becomes a liquid A solid melts because the kinetic energies of the particles increase and overcome the attractive forces holding them together

Density Generally, substances are most dense in the solid state. Solids are slightly denser than liquids and much denser than gases. This is because the particles are more closely packed.

Diffusion Solids have an extremely low rate of diffusion. It is millions of times slower in solids than in liquids.