Chemical Processes
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Professor Diamond continues her discussion of the nervous system beginning with processes - extensions of the soma. She describes axons, dendrites and the types of synapses: axodendritic, axoaxomic, axosomatic, and dendrodentritic. She then describes how neurotransmitters travel from the presynaptic terminal of an axon to the postsynaptic terminal of a dendrite in an axodendritic synapse. Professor Diamond continues with neuron...more
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The Big Bang created the physical universe. Of course life is part of this physical universe, but the immediate building blocks of life are chemicals. Before the Big Bang, words such as “time” had no meaning, but even in the first few minutes there could be no chemistry since there were no atoms. The nuclei of some of the lighter elements formed within minutes, atoms some time later, and elements heavier than lithium were forged in the...more
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August 21, 2008 presentation by Stacey Bent for the Stanford University Office of Science Outreach's Summer Science Lecture Series. Meeting the world's growing energy needs in a sustainable fashion is one of the most pressing problems of our time. Professor Bent introduces the scope of the energy problem and some of the options for sustainable energy, then will focus on two main devices: solar cells and fuel cells. Solar cells convert...more
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Professor McBride begins by using previous examples of "pathological" bonding and the BH3 molecule to illustrate how a chemist's use of localized bonds, vacant atomic orbitals, and unshared pairs to understand molecules compares with views based on the molecule's own total electron density or on computational molecular orbitals. This lecture then focuses on understanding reactivity in terms of the overlap of singly-occupied molecular...more
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Going back to 1998, Symantec was best known for Norton utilities and Norton anti-virus, says Thompson. When he arrived in 1999, right after windows 1998 was launched. Symantec had had a bad series of quarter. In his first 100 days, he looked at the company product portfolio and found products that were not of strategic value. The brightest star was Norton anti-virus. Symantec had viewed itself as a consumer oriented desktop software...more
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Professor McBride outlines the course with its goals and requirements, including the required laboratory course. To the course's prime question "How do you know" he proposes two unacceptable answers (divine and human authority), and two acceptable answers (experiment and logic). He illustrates the fruitfulness of experiment and logic using the rise of science in the seventeenth century. London's Royal Society and the "crucial" experiment...more
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Continuing the examination of molecular orbital theory as a predictor of chemical reactivity, this lecture focuses on the close analogy among seemingly disparate organic chemistry reactions: acid-base, SN2 substitution, and E2 elimination. All these reactions involve breaking existing bonds where LUMOs have antibonding nodes while new bonds are being formed. The three-stage oxidation of ammonia by elemental chlorine is analyzed in the...more
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Professor McBride begins by following Newton's admonition to search for the force law that describes chemical bonding. Neither direct (Hooke's Law) nor inverse (Coulomb, Gravity) dependence on distance will do - a composite like the Morse potential is needed. G. N. Lewis devised a "cubic-octet" theory based on the newly discovered electron, and developed it into a shared pair model to explain bonding. After discussing Lewis-dot notation...more
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Continuing the discussion of Lewis structures and chemical forces from the previous lecture, Professor McBride introduces the double-well potential of the ozone molecule and its structural equilibrium. The inability for inverse-square force laws to account for stable arrangements of charged particles is prescribed by Earnshaw's Theorem, which may be visualized by means of lines of force. J.J. Thomson circumvented Earnshaw's prohibition on...more
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This lecture continues the discussion of the HOMO/LUMO view of chemical reactivity by focusing on ways of recognizing whether a particular HOMO should be unusually high in energy (basic), or a particular LUMO should be unusually low (acidic). The approach is illustrated with BH3, which is both acidic and basic and thus dimerizes by forming unusual "Y" bonds. The low LUMOs that make both HF and CH3F acidic are analyzed and compared...more
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After pointing out several discrepancies between electron difference density results and Lewis bonding theory, the course proceeds to quantum mechanics in search of a fundamental understanding of chemical bonding. The wave function ψ, which beginning students find confusing, was equally confusing to the physicists who created quantum mechanics. The Schrödinger equation reckons kinetic energy through the shape of ψ. When ψ curves toward...more
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Andy Friere, Co-founder and CEO of Axialent, describes the customer-focused culture archetype, one of the five basic cultural archetypes into which organizations fall: 1) Achievement, 2) Innovation, 3) One-team, 4) People-first or 5) Customer-focused. Specifically, Friere suggests that customer-focused cultures value flexibility to service customer needs above other potential activities. Friere describes the behaviors, symbols and...more
