CHEM 125a - Lecture 2 - Force Laws, Lewis Structures and Resonance

Lecture 2 - Force Laws, Lewis Structures and Resonance


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 and formal charge, Professor McBride shows that in some "single-minimum" cases the Lewis formalism is inadequate and salvaging it required introducing the confusing concept of "resonance."


Professor McBride's website resource for CHEM 125 (Fall 2008)

This website may include third-party materials pertaining to relevant topics, provided for the user's convenience. Yale does not control or take responsibility for the content of any off-site pages or linked sites.


Reading assignments, problem sets, PowerPoint presentations, and other resources for this lecture can be accessed from Professor McBride's on-campus course website, which was developed for his Fall 2008 students. Please see Resources section below.

Course Media





Low Bandwidth Video

mov [100MB]

High Bandwidth Video

mov [500MB]