THE STUDY OF RADIOACTIVE DECAY

Rutherford's experiment

The study of radioactive decay led scientists to believe that transmutations from one element to another could be achieved by adding protons to the nucleus. Rutherford was the first to successfully perform a transmutation in 1919. In Rutherford’s experiment, a container filled with nitrogen gas was used, along with a radioactive source that emitted alpha particles. A silver foil, thick enough to absorb the alpha particles that were not absorbed by the nitrogen gas, was placed at one end of the container. A zinc sulfide screen behind the foil recorded the scintillations of particles that had enough energy to pass through the foil. A scintillation is a flash of light produced in certain media by absorption of an ionizing particle or photon. These scintillations could then be observed by a microscope.

The following nuclear equation represents the transformation product of nitrogen when bombarded by alpha particles:

The validity of the equation was supported by the detection of oxygen gas in the container after the alpha bombardment of pure nitrogen. The alpha bombardment of nitrogen results in proton emission.

Chadwick's bombardment

Other bombardments produce differing particle emissions. An important bombardment was performed in 1932, by Chadwick. This experiment led to the discovery of the neutron. The following is Chadwick’s nuclear equation:

Numerous similar bombardments have since been performed, and found to produce neutrons. Since the neutron is not electrically charged, it penetrates atomic nuclei more readily than that of protons or alpha particles. It is known that the neutron has become a significant nuclear bullet.

 

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