ABSTRACT
Chapter 4 reviews the configuration of electrons in atoms of different elements and discusses how these configurations control the nature of bonding between different atoms.1-8 Metallic, ionic, covalent, and van der Waals bonding are described. Some concepts of crystal structure, polymorphism, and noncrystalline structures are introduced. The chapter concludes with a brief review of organic structures. A discussion of organic materials is included for the purpose of comparison, but also because organic materials are used extensively in ceramic fabrication processes.9-12
An atom can be visualized in a simplified manner as a positively charged nucleus surrounded by negatively charged electrons. The energy of the electrons varies such that specific electrons are located in specific shells around the nucleus. These are called quantum shells. Each shell is referred to by a principal quantum number n, where n 1, 2, 3, … . The total number of electrons in a shell is 2n2. Thus the lowest-energy quantum shell (n 1) has only 2 electrons and successively higher energy shells have 8 (n 2), 18 (n 3), 32 (n 4), and so on, electrons, respectively.
