All of the matter around you, whether it be synthetic materials in your room or natural materials outside, is composed of chemical substances. We have learned that these substances are built from atoms in arrangements that are stabilized by chemical bonds. But we have not looked closely at those bonds, or attempted to understand why they exist or how they affect the characteristics of the materials on the observable, macroscopic scale.

Chemical bonding is a big subject. Fortunately, however, there are some basic ideas that are really useful. For instance, you can quite quickly come to look at a substance and make a good guess on whether or not it contains any of the metallic elements. You also can look at a formula and predict that a substance will melt or burn if you heat it in an oven. The secrets here are related to understanding the nature of bonding, and how the microscopic connects to the macroscopic.