Solids resemble liquids in having a definite volume, but differ from both liquids and gases in having a definite shape. The molecules of a solid, like those of a liquid, are very close together, but whereas the molecules of a liquid are free to move around, those of a solid have less thermal energy and are held fixed in their places by intermolecular forces . Their only movement is a vibration about a fixed position. A solid changes to a liquid when its temperature is raised to its melting point .
Solids are of various types.
Metals, their alloys, some nonmetals, and ionic chemical compounds are crystalline in form. Some solids, e.g., chalk and clay, have no regular structure and are called amorphous. Properties in which solids differ from one another include density, hardness, malleability, ductility, elasticity, brittleness, and tensile strength. Listing from Electric Library , a pay service. Copyright 2001 Infonautics Corporation .