A Periodic Table of the Structure of Atoms and Its Relation to Ion-Formation and Valence.

Introduction.-For the purpose of studying the interpretations which the recently acquired knowledge of the structure of atoms might afford as to tendencies of elements to form ions and to exist in definite valence states, the authors compiled from spectroscopic publications of the last three years the values of the energies attending the removal of the various electrons from the outer shells of the atoms and ions of the first twenty-six elements (higher elements not being included, since the spectral data have as yet been too incompletely interpreted). And a chart was prepared showing the number, the quantum states, and the energies of removal of these electrons. The data upon which the chart is based and the detailed discussion of it in relation to the chemical properties mentioned are to be published in full in the Journal of the American Chemical Society;* but the interest which the matter might have for scientists in other fields has led to the presentation in these PROCIEDINGS of the chart and a summary of the conclusions reached as to ion formation and valence. In the assembling and interpretation of the spectroscopic data we have been greatly assisted by the advice of Prof. Ira S. Bowen of this Institute, by whose experimental researches, made in association with Dr. R. A. Millikan, the data for the chart have in large measure been made available. This paper has, moreover, been possible only through the recent interpretations of electron distribution by Main-Smith' and Stoner2 and of complex spectra by Russell and Saunders,3 Pauli,4 Heisenberg' and Hund.6 Description of the Chart.-The chart is shown on page 740. Along the axis of abscissas is plotted the atomic number of the element, which also represents the positive charge on the nucleus of its atom and ions, as well as the total number of electrons around the nucleus of the