Soddy, Frederick, radioactivity studied

The last sites visited in this chapter are associated with Ernest Rutherford and Frederick Soddy, pioneers in the study of radioactivity. Radioactivity is one of the phenomena that led chemists and physicists to understand that atoms were not indestructible or indivisible. 

In spite of all the new approaches which illuminated the outer regions of the atom, the center or nucleus of the atom continued to remain a bundle of uncertainties. Something of the composition of the nuclei of a few elements was already known. This information came from a study of the spontaneous disintegration of radium and other radioactive elements, such as thorium, polonium, uranium, and radon. These elements break down of their own accord into simpler elements. Soon after the Curies discovery of radium, Rutherford and Frederick Soddy, his student and collaborator, had found that the spontaneous breaking down of radium resulted in the emission of three types of rays and particles. Radium ejected alpha particles (ionized helium atoms), beta particles (electrons), and gamma rays (similar to X-rays). In radioactive elements, at least, it was believed that the nucleus contained electrons, protons, and electrified helium particles. 

The cathode-ray tubes were also found to eject positive ions in the opposite direction from the electrons. These canal rays were comprised of much more massive particles. J.J. Thomson (1906 Nobel Prize in Physics) used a magnetic field to bend the paths of these ions and record their collisions on film. He discovered that pure neon gas produced two masses, 20 and 22, due to isotopes. The term was coined by Frederick Soddy (1921 Nobel Prize in Chemistry) during his studies of radioactive elements having the same chemical but different radioactive properties. The separation of positive ions using a magnetic field followed by recording them on a photographic plate is the basis of mass spectrometry, developed by Francis W. Aston (1922 Nobel Prize in Chemistry). ... 

Results of this sort were obtained in 1914 by the American chemist Theodore William Richards (1868-1928). They confirmed the deductions about the existence of isotopes that had been made in 1913 by the English chemist Frederick Soddy (1877-1956) from the study of radioactive transformations of uranium and thorium. 

Marie and Pierre Curie examined the radiation emitted by radium. They found that all substances near the radiation source became radioactive themselves. The activity even remained some time after the removal of the emitting radium. It was questioned whether there is some radioactive force that was transferred with the radiation and was induced in the receiving substance. In 1900 F. Dom in Halle, Germany, reported on a study of an isotope emanating from radium and, because of that, certainly incorrectly, was credited with the discovery of radon. In fact Ernest Rutherford (1871-1937) and Frederick Soddy (1877-1956) were the first to isolate radon and also the first to really understand the nature of radon. In the first decade of 1900 they worked at McGill University in Montreal, Canada, and carried out very comprehensive work on radioactivity [52.10]. They discovered that the emanation from radium was a gas of the same type as the noble gases. Ramsay at University College in London completed the spectral work. He showed that the spectrum of radon resembled that of xenon. He also showed that the formation of radon was accompanied by the simultaneous production of helium, as he also observed its spectrum. This observa-... 

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