Lecture Description
Professor McBride uses a hexagonal "benzene" pattern and Franklin's X-ray pattern of DNA, to continue his discussion of X-ray crystallography by explaining how a diffraction pattern in "reciprocal space" relates to the distribution of electrons in molecules and to the repetition of molecules in a crystal lattice. He then uses electron difference density mapping to reveal bonds, and unshared electron pairs, and their shape, and to show that they are only one-twentieth as dense as would be expected for Lewis shared pairs. Anomalous difference density in the carbon-fluorine bond raises the course's second great question, "Compared to what?"
Course Description
This is the first semester in a two-semester introductory course focused on current theories of structure and mechanism in organic chemistry, their historical development, and their basis in experimental observation. The course is open to freshmen with excellent preparation in chemistry and physics, and it aims to develop both taste for original science and intellectual skills necessary for creative research.
Related Resources
Lecture Resources
Course Index
- How Do You Know: Divine or Human Authority vs Logic and Experiment
- Force Laws, Lewis Structures and Resonance
- Double Minima, Earnshaw's Theorem, and Plum-Puddings
- Coping with Smallness and Scanning Probe Microscopy
- X-Ray Diffraction
- Seeing Bonds by Electron Difference Density
- Quantum Mechanical Kinetic Energy
- One-Dimensional Wave Functions
- Chladni Figures and One-Electron Atoms
- Reality and the Orbital Approximation
- Orbital Correction and Plum-Pudding Molecules
- Overlap and Atom-Pair Bonds
- Overlap and Energy-Match
- Checking Hybridization Theory with XH3
- Chemical Reactivity: SOMO, HOMO, and LUMO
- Recognizing Functional Groups
- Reaction Analogies and Carbonyl Reactivity
- Amide, Carboxylic Acid and Alkyl Lithium
- Oxygen and the Chemical Revolution (Beginning to 1789)
- Rise of the Atomic Theory (1790-1805)
- Berzelius to Liebig and Wöhler (1805-1832)
- Radical and Type Theories (1832-1850)
- Valence Theory and Constitutional Structure (1858)
- Determining Chemical Structure by Isomer Counting (1869)
- Models in 3D Space (1869-1877); Optical Isomers
- Van't Hoff's Tetrahedral Carbon and Chirality
- Communicating Molecular Structure in Diagrams and Words
- Stereochemical Nomenclature; Racemization and Resolution
- Preparing Single Enantiomers and the Mechanism of Optical Rotation
- Esomeprazole as an Example of Drug Testing and Usage
- Preparing Single Enantiomers and Conformational Energy
- Stereotopicity and Baeyer Strain Theory
- Conformational Energy and Molecular Mechanics
- Sharpless Oxidation Catalysts and the Conformation of Cycloalkanes
- Understanding Molecular Structure and Energy through Standard Bonds
- Bond Energies, the Boltzmann Factor and Entropy
- Potential Energy Surfaces, Transition State Theory and Reaction Mechanism
