Callister Chapter 2: Atomic Structure and Interatomic Bonding

The way atoms are arranged and how they interact with each other within a material directly affect the material’s properties. The most classic example of this is the comparison between graphite and diamond, both of which are made of carbon but which have very different properties. In graphite, each carbon atom is bonded to three other carbons, forming sheets that easily slide past each other. In diamond, each atom is bonded to four other carbons, forming strong tetrahedra throughout the crystal, making diamond the hardest known material. In this chapter, we will discuss atomic structure, bonding forces and energies, and types of bonds.

Atomic structure

-an atom consists of a tightly bound nucleus of protons and neutrons that are surrounded by an electron cloud

-towards the end of the nineteenth century, it became clear than many phenomena involving electrons could not be explained with classical mechanics, leading to the birth of quantum mechanics

-the main stipulation of quantum mechanics is that electrons have quantized energies (they can only have specific values of energy)

-two of the main models used to describe atoms are the Bohr atomic model and the wave-mechanical model

-the Bohr model assumes that electrons revolve around the nucleus in discrete orbitals, as seen in the figure below

Callister Chapter 1: Introduction

Now that it’s summer, I am finally making good on my promise to post chapter summaries of Materials Science and Engineering: An Introduction, better known as the Callister textbook. There are 22 chapters in total and approximately 11 weeks until Hell Month aka the candidacy exam, so my goal is to cover about two chapters a week. That being said, if there is any topic/chapter that you find especially interesting—or if you just feel like being a super awesome friend—feel free to talk to me about writing your own summary that I can add to this blog!

Materials science and engineering plays an integral role in life as we know it—indeed, it not only influences our everyday lives, but has governed the advancement of humankind so much so that early civilizations are now described by their materials development (Stone Age, Bronze Age, Iron Age). This chapter describes the purpose of materials science and engineering and classifies materials into several main categories.

The purpose of materials science and engineering

-materials science is the study of the relationship between a material’s structure and its properties

-materials engineering is the design of a material’s structure to produce desired properties

-from small scale to large scale, a material’s structure—that is, its internal arrangement—includes subatomic, atomic, microscopic, and macroscopic structure

-a material’s properties fall into the classifications of mechanical, electrical, thermal, magnetic, optical, and deteriorative

-the way a material is processed influences its structure, which in turn influences its properties, and ultimately determines its performance