Passivity of Iron and other Metals

Abstract

IT is well known that the principal metals which show the phenomena of passivity are chromium, manganese, iron, cobalt and nickel. These elements have this in common that they form divalent ions, and that while possessing electrons, on Bohr's theory, in the 4th-quantum orbit, their 3rd-quantum orbits are incomplete. My view is that these elements when in the active state have each two electrons in the 4th-quantum orbit, and that they become passive when one of these electrons is removed to a 3rd-quantum orbit. This implies that the usual chemical and physical agencies which make an active metal passive or a passive one active, merely, in some way, induce these electronic changes. It is for the physicists to say if this be possible. There is, however, no a priori objection to this view since transitions between 3rd- and 4th - quantum orbits of these elements are known to occur readily. I do not suppose a suggestion of this kind will explain the whole of the phenomena of passivity, which is admittedly complex, but I offer it as a contribution towards the explanation of the more obvious phenomena.