42:7.9

The thirty innermost orbital electrons have individuality, but their energy systems tend to intermingle, extending from electron to electron and well-nigh from orbit to orbit. The next thirty electrons constitute the second family, or energy zone, and are of advancing individuality, bodies of matter exerting a more complete control over their attendant energy systems. The next thirty electrons, the third energy zone, are still more individualized and circulate in more distinct and definite orbits. The last ten electrons, present in only the ten heaviest elements, are possessed of the dignity of independence and are, therefore, able to escape more or less freely from the control of the mother nucleus. With a minimum variation in temperature and pressure, the members of this fourth and outermost group of electrons will escape from the grasp of the central nucleus, as is illustrated by the spontaneous disruption of uranium and kindred elements.