The chemistry of the radio-elements / by Frederick Soddy.

  • Soddy, Frederick, 1877-1956.
Date:
1914
Catalogue details

Licence: In copyright

Credit: The chemistry of the radio-elements / by Frederick Soddy. Source: Wellcome Collection.

    50/64 (page 38)
    Although physicists have not yet advanced their theories of atomic structure to the point of giving a reasonable explanation of the Periodic Law (Figs. 2 and 3)—and, indeed, have hardly got beyond the consideration of a few of the simplest elements—the advances dealt with here do to some extent contribute material data to the discussion of the nature of atomic structure. It is clear that the charges on the a- and |Q-particles do definitely come from the atom, and are not, as the writer once tried unsuccessfully to show in the case of the a-particle, derived subsequently to the disintegration, as by collision with the matter in the path of the ray. It is true that, in the best-known cases of a-ray disintegrations, three rather than two charges of positive electricity appear to be liberated from a system previously electrically neutral, one being found on the recoil atom.®^ But this may or may not be of significance, be- cause the emission of a single ^-particle would be very difficult to detect, and might account for the third positive charge. But the shift of place of the atom in the Periodic Table is most naturally explained on the view that the charges expelled with the rays are intrinsic to the atomic structure. Fajans ^ has argued that, since the changes of properties suffered in radioactive change are the same as those in electro-chemical change, radioactive changes must be con- cerned with the same part of the atomic system as ordinary chemical change, contrary to the accepted view. But this conclusion does not stand closer examination. Clearly upon it, for example, uranium in the uranous salts should be non- separable from thorium, so long as it were prevented from altering its tetravalency. There is a marked analogy in chemical properties between uranous and thorium salts which gives some colour to the supposition, but an examination, still unpublished, by Fleck and the writer, showed that the