Cosmo Learning
Cosmo Learning: Modern Physics: Quantum Mechanics
A collection of video lectures from a modern physics course that focuses on quantum mechanics. The course is taught at Stanford University. The course includes ten lectures that vary in length.
Simon Fraser University
Chem1 Virtual Textbook: Movement of the Electron
Acting as a subtopic of the General Chemistry Virtual Textbook's section on Atoms and the Periodic Table, this site seeks to answer the question, "Why doesn't the electron fall into the nucleus?"
Dartmouth College
Dartmouth College: Chem Lab: Electrons in a Box
This site has an interactive component that allows you to change the mass, number of electrons and the length of the box and see how it affects the energy levels. Requires Java.
Other
Using Curly Arrows in Reaction Mechanisms
This page explains the use of curly arrows to show the movement both of electron pairs and of single electrons during organic reaction mechanisms.