Atomic Models and X-Ray Spectra

Abstract

IT is universally assumed that the atom of an element can form a Saturnian system with more than one ring of rotating electrons, and this idea is used in particular by Moseley in the theoretical discussion of his recent experiments. But in an Adams prize essay, not yet published in extenso, this is shown to be impossible. If the law of repulsion between two electrons, or of attraction between electron and nucleus, is that of the inverse square, more than one coplanar ring cannot exist. All the electrons in any plane must lie in the same ring, and even if they are in different planes, the radii of the rings must be nearly equal. A consideration of a simple case will illustrate this. For example, it is at first sight probable that the system in the accompanying diagram, consisting of two coplanar rings of three electrons each, symmetrically arranged with all the angles equal to 60°, can exist with some angular velocity ω, if the radii of the outer and inner rings are a and b, the latter being, much smaller than a. But it is easily shown that the conditions of steady rotation, of such a system are—