Half a century before direct experimental observation became possible, most structures of organic molecules were assigned by inspired guessing based on plausibility. But Wilhelm Körner developed a strictly logical system for proving the structure of benzene and its derivatives based on isomer counting and chemical transformation. His proof that the six hydrogen positions in benzene are equivalent is the outstanding example of this chemical logic but was widely ignored because, in Palermo, he was far from the seats of chemical authority. Problem sets/Reading assignment: Reading assignments, problem sets, PowerPoint presentations, and other resources for this lecture can be accessed from Professor McBride’s on-campus course website, which was developed for his Fall 2008 students. Please see Resources section below. Professor McBride's web resources for CHEM 125 (Fall 2008)