MATERIALES EN INGENIERIA 4º CHAPTER

Publisher Summary

To understand the origin of material properties such as Young's modulus, focus is needed on materials at the atomic level. Two things are very important for determining the modulus: the forces that hold atoms together (the interatomic bonds), which act like little springs linking one atom to the next in the solid state, and the ways in which atoms pack together (the atom packing). This chapter takes a look at the forces that bind atoms together—the springs. The various ways in which atoms can be bound together involve: primary bonds—ionic, covalent, or metallic bonds—that are all relatively strong (they generally melt between 1000 and 4000 K), and secondary bonds—van der Waals and hydrogen bonds that are both relatively weak (they melt between 100 and 500 K). It should remembered, however, when listing distinct bond types that many atoms are really bound together by bonds that are a hybrid of the simpler types (mixed bonds). It is because of these primary and secondary bonds that matter condenses from the gaseous state to give liquids and solids. Five distinct condensed states of matter, differing in their structure and the state of their bonding, can be identified here. The chapter concludes with a discussion of interatomic forces.