65 - The structure of materials

Abstract

This chapter focuses on the structure of materials. Materials are the collective name given to substances that exist in nature in a stable state. They can be pure elements, for example, chlorine gas, bromine liquid or metallic copper solid, and pure compounds of elements. The structure of materials is an extension of the bonding or the combination of atoms into elements or compounds considers only the constituent particles. However, the structure of materials and their properties takes into account the vast number of particles that make up observable masses of material. For example, when sodium chloride is considered, only enough particles are used to define the unit cell. The structures of solid materials are all based upon particles being held in a regular three-dimensional pattern. The properties of a solid depend on the nature and intensity of the forces holding the particles in place. On the other hand, when solids undergo phase changes to become liquids and gases, their structural properties change completely and behave in the same way as materials that exist as liquids and gases at room temperature.