The Structure of the Atom¹

Abstract

III.—The Nucleus. IN the previous articles we discussed the nucleus mainly in connection with the idea of atomic number. We shall now return to the characters of the nucleus itself; but before doing so it is necessary to say something about the atom as a whole. Comparatively little is known about the electrons surrounding the nucleus—it is not even universally agreed whether they are at rest or in motion—but a successful beginning has been made by the Bohr spectrum theory, which applies mainly to the specially simple case of hydrogen. On the same lines Sommerfeld has also had some success with the X-ray spectra. It is quite certain, as in all questions of atomics, that the laws of classical dynamics do not hold, and the principal method in research at present consists in a judicious mixture of these laws with the quantum theory. This latter theory is definitely contradictory not only to the laws of mechanics, but also to almost any conceivable modification of them, and its chief justification, an entirely adequate one, is the astounding success with which it has been extended over more and more branches of physics.