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Conclusion (Atomic Disintegration and Radioactive Transformations of Atoms)

المؤلف:  GEORGE A. HOADLEY

المصدر:  ESSENTIALS OF PHYSICS

الجزء والصفحة:  p-517

2025-12-30

481

Since electrons separate from the atoms of radio-active substances it is evident that, however slow the process, there is going on a disintegration or breaking down of the atom. This expulsion from the atom is accompanied by the production of such an amount of heat that the temperature of radium bromide is sometimes as much as five degrees Centigrade above that of the surrounding air. In order to understand the significance of this atomic disintegration it must be followed a step farther. Certain radioactive substances, as radium, actinium, and thorium, emit a substance like a heavy gas that is endowed with temporary radio-active properties. This is called the emanation. If kept for a number of days, it loses a large portion of its radioactivity, and on being examined with the spectroscope, shows the well-defined lines of the element helium, which were not present when the emanation was first formed. This seems to indicate a change from one element into another. Perhaps it is rather an indication that both these elements are but forms of a third and possibly unknown element.

To Dalton belongs the credit of giving the atom its place of honor as the fundamental unit of the chemist. It has taken the combined research of many physicists since Dalton's time to establish the complicated structure of the atom and to show us at least a part of its function in the formation of matter.