1. Electron Configuration & promoting electrons
From an animation posted by John Gelder

2. http://cheminfo. chem. ou. edu/~mra/Laboratory%20Simulations/Aufbau
“The electron configuration animation was done by Nancy Gettys, Judd Wheeler and myself for an AP Chemistry ‘By Satellite’ course that I taught in the early 1990's.”
Dr. John Gelder Professor of Chemistry Department of Chemistry Oklahoma State University

3. Review s p d f

51. http://cheminfo. chem. ou. edu/~mra/Laboratory%20Simulations/Aufbau
“The electron configuration animation was done by Nancy Gettys, Judd Wheeler and myself for an AP Chemistry ‘By Satellite’ course that I taught in the early 1990's.”
Dr. John Gelder Professor of Chemistry Department of Chemistry Oklahoma State University