In solving my problem 2.a. -- you have to remember that his is the hydrogen atom. Equations and figures on page 467 of your text might be helpful. -- Andrew J. Pounds, Ph.D. (pounds_aj at mercer.edu) Professor of Chemistry and Computer Science Mercer University, Macon, GA 31207 (478) 301-5627 http://faculty.mercer.edu/pounds_aj