3. Double Minima, Earnshaw's Theorem and Plum-Puddings
Freshman Organic Chemistry (CHEM 125)
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 structure by postulating a "plum-pudding" atom. When Rutherford showed that the nucleus was a point, Thomson had to conclude that Coulomb's law was invalid at small distances.
00:00 - Chapter 1. Distinguishing Equilibrium and Resonance
06:37 - Chapter 2. The Structure and Surface Potential of Ozone
20:57 - Chapter 3. Visualizing Electrostatic Force: Earnshaw's Theorem
35:07 - Chapter 4. J. J. Thomson's Plum Pudding Model
Complete course materials are available at the Open Yale Courses website: http://open.yale.edu/courses
This course was recorded in Fall 2008.