Passivity, Catalytic Action, and other Phenomena

Abstract

THE writer's view of the passivity of chromium, manganese, iron, cobalt and nickel (NATURE, March 28, 1925, 115, p. 455) may now be extended and correlated with the recent work of H. S. Taylor (Proc. Roy. Soc., 1925, A, 108, p. 105) and of E. F. Armstrong and T. P. Hilditch (ibid., p. 111) on catalytic action at the surface of nickel, with that of J. Heyrovský (Rec. trav. chim., 1925, 44, p. 499) on overvoltage, and with that of T. M. Lowry on the nature of chemical action. This view is based on Bohr's distribution of electrons within the atom. It supposes that in the elements mentioned the number of electrons in the outermost orbit is “ideally” between one and two, and is therefore either one or two, and that in consequence the atoms of such elements can never be electrically neutral in the same sense as atoms of sodium or of zinc. The experimental evidence favours calling the state with one electron in the outer orbit passive, and that with two electrons in the outer orbit active. The difference in potential between the two states of each of these metals is about 1 volt.