Chemistry has seen many advances in a relatively short time, driven by scientists who wove seemingly unrelated observations into coherent theorems that explained molecular behavior. Before 1860, the empirical formula for water (H₂O) was thought to be OH, and virtually nothing was known about the structure of organic compounds except that they were composed mostly of carbon and hydrogen. In the intervening years, a great deal of thought was devoted to developing an understanding of molecular behavior, and the results of that work are remarkable. Only a few decades ago, it was common knowledge that no microscope would ever allow human eyes to “see” a molecule. But now we are able to view (and even arrange) individual atoms using the modern techniques of scanning tunneling microscopy (STM) and atomic force microscopy (AFM).