Open Yale CoursesCHEM 125: Freshman Organic ChemistryLecture 6 - Seeing Bonds by Electron Difference Density<< previous session| next session >>Overview:Professor McBride uses a hexagonal "benzene" pattern and Franklin's X-ray pattern of DNA, to continue hisdiscussion of X-ray crystallography by explaining how a diffraction pattern in "reciprocal space" relates tothe distribution of electrons in molecules and to the repetition of molecules in a crystal lattice. He then useselectron difference density mapping to reveal bonds, and unshared electron pairs, and their shape, and toshow that they are only one-twentieth as dense as would be expected for Lewis shared pairs. Anomalousdifference density in the carbon-fluorine bond raises the course's second great question, "Compared to what?"Problem sets/Reading assignment:Reading assignments, problem sets, PowerPoint presentations, and other resources for this lecture can beaccessed from Professor McBride's on-campus course website, which was developed for his Fall 2008
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