Radium, discovery disintegration

The actual discovery was made by Mile. Marguerite Perey at the Curie Institute in Paris. In 1939 she purified an actinium preparation by removing all the known decay products of this element. In her preparation she observed a rapid rise in beta activity which could not be due to any known substance. She was able to show that, while most of the actinium formed radioactinium, an isotope of thorium, by beta emission, 1.2 0.1 per cent of the disintegration of actinium occurred by alpha emission and gave rise to a new element, which she provisionally called actinium K, symbol AcK (35, 36). This decayed rapidly by beta emission to produce AcX, an isotope of radium, which was also formed by alpha emission from radioactinium. Thus AcK, with its short half-life, had been missed previously because its disintegration gave the same product as that from the more plentiful radioactinium. 

Measurement of radioactiviry, as an analytical tool became possible after the discoveries of A.H.Becquerel(uranium radiation 1896), Pi re Marie Curie (polonium radium in 1898), Sir E. Rutherford (identification of Becquerel rays as consisting of alpha-, beta and gamma-particles) and of F.Soddy(phenomenon of nuclear disintegration, in 1902)... 

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. 

In 1903, Ramsay and Soddy 0 announced the discovery of the fact that helium was a product of the atomic disintegration of radium, one gram of which produces about 0.45 cubic millimeter of helium per day. Later it was found that other radioactive substances also yield helium and that the charged helium atom is the alpha particle. 

In 1903 Ramsay and Soddy made a sensational discovery, namely that helium is a disintegration product of radium. 

CURIE. A common unit of measurement for radioactivity. One curie is equal to 37 billion disintegrations per second or 37,000,000,000 becquerel, the metric unit for measuring radioactivity. The unit, abbreviated Ci, honors the Polish-French scientist Marie Curie (1867-1934), who is credited with coining the term radioactive. Curie and her husband Pierre (1859-1906) received the 1903 Nobel Prize in Physics in recognition of their investigations of radioactivity, sharing the award with Henri Becquerel. Marie Curie was also recognized with a second Nobel Prize, the 1911 award in Chemistry, for her discoveries of the elements radium and polonium. 

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