Atomic masses shown in parentheses indicate the most stable isotope (longest half-life) known.
Electron configuration data was taken from Douglas C. Giancoli's Physics, 3rd edition. Average atomic masses were taken from Kenneth W. Whitten's, Kenneth D. Gailey's, and Raymond E. Davis' General Chemistry, 3rd edition. In the latter book, the masses were specified as 1985 IUPAC values.
Lessons In Electric Circuits copyright (C) 2000-2003 Tony R. Kuphaldt, under the terms and conditions of the Design Science License.