Tutorials in Materials Science: Bond Energy and Crystal Energy

The properties of materials are deeply connected to their stability in the solid state. When comparing the strength of bonding in different solids, several factors come into play, including the strength of individual bonds, the type of bonding, crystal structure, and chemical stoichiometry. In this video, you'll explore the energies of bonds in solids and learn how the strength of a single bond can be used to calculate the molar stability of a crystalline solid. Tailored for sophomore-level students in Materials Science, the video begins with an analysis of individual atomic bonds. We’ll explore how different bonding models influence bond potentials and examine how the energy of a single bond can be used to calculate the molar cohesive energy of the solid. Since a mole of solid contains many bonds, we’ll delve into the importance of accurately counting bonds from the crystal structure. You’ll also learn when it’s appropriate to consider only nearest-neighbor bonds and when longer-range interactions are essential. For ionic systems, long-range interactions extending well beyond nearest neighbors must be taken into account, which is where the Madelung constant becomes crucial for calculating the cohesive energy of ionic solids. The video also highlights common pitfalls in comparing bonding strength between different solids and how these relate to physical properties such as melting points. In the final section, we’ll walk you through how to calculate the most reliable metric: the bonding energy per atom, ion, or molecule in the solid.