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Melting point and molecular symmetry are discussed. A simple question about melting points brought the motivation for the study: Why does methane have such a high melting point vs the higher alkanes? Topics discussed include Carnelley's rule and evidence for it, application of this rule to various crystal classes, Gibbs energy, and the enthalpy/entropy diagram. Compounds of high molecular symmetry are found to have high melting points, in general. The rule comes from a 2-part 1882 paper by Thomas Carnelley that summarizes a survey of melting points of many compounds.

A hands-on scanning probe microscopy (SPM ) laboratory for undergraduates in chemistry to use with a tomic force microscopy (AFM) to look at well-defined crystalline materials is presented. A series of the combination SP M-AFM laboratory exercises with the goal of enhancing comprehension of atomic and molecular scale concepts and providing hands-on experience to help undergraduate students understand the theory, basis, and o peration of SPM. Topics include scanning tunneling microscopy (STM) images of highly ordered pyrolytic graphite ( HOPG), AFM image of mica, and interpretations thereof.