Solids<br />Chapter 12.2<br />Objectives:<br />Describe the motion of particles in solids and the properties of solids according to the kinetic-molecular theory.<br />Distinguish between the two types of solids.<br />Describe the different types of crystal symmetry. Define crystal structure and unit cell.<br />
Properties of Solids and Kinetic-Molecular Theory<br />Particles are more closely packed.<br />Intermolecular forces are much more effective in solids.<br />Hold molecules in fixed position, only vibration movement<br />More ordered than other phases<br />Two types of Solids<br />Crystalline solids:<br />Consist of crystals, which are, a substance in which the particles are arranged in an orderly, geometric, repeating pattern.<br />Amorphous solid:<br />Solids whose particles are arranged randomly<br />Ex: glass and plastic<br />
Definite Shape and Volume<br />Tightly packed particles<br />Very little space for compression<br />Do not flow b/c fixed position of particles <br />Amorphous solids do flow (random arrangement)<br />Definite Melting Point<br /><ul><li>Melting
Physical change of a solid to a liquid by the addition of heat. (Temperature which a solid becomes a liquid)
Kinetic energy of particles overcome attractive forces holding them together.
Substances that retain certain liquid properties even at temperatures at which they appear to be solid.</li></li></ul><li>High Density and Incompressibility<br />Particles are more closely packed together<br />Why are wood and cork compressible?<br />They are not!!<br />They contain pores filled with air, which is what can be compressed<br />Low Rate of Diffusion<br /><ul><li>Can it happen?
YES, But millions of times slower than liquids and gases</li></li></ul><li>Crystalline Solids<br />Crystal Structure:<br />Total 3-D arrangement of particles is a crystal – lattice<br />Unit Cell:<br />Smallest portion of a crystal lattice that show the 3-D pattern of the entire lattice <br />Seven types of symmetry <br />Calcite<br />Trigonal<br />Fluorite<br />Cubic<br />Emerald Hexagonal<br />Chalcopyrite Tetragonal<br />Aragonite Orthorhombic<br />Azurite Monoclinic<br />Rhodonite<br />Triclinic<br />
Binding forces in Crystals<br />Four Types<br />Ionic Crystals<br /><ul><li>Consist of positive and negative ions