Polonium history

The discovery and the history of radioactivity is closely connected to that of modern science. In 1896 Antoine Henri Becquerel observed and described the spontaneous emission of radiation by uranium and its compounds. Two years later, in 1898, the chemical research of Marie and Pierre Curie led to the discovery of polonium and radium. 

FIGURE 2.6 Marie Sklodowska Curie (1867-1934). When Marie Curie presented her doctoral thesis, it was described as the greatest single contribution of any doctoral thesis in the history of science. In 1903 Henri Becquerel, Maire Curie, and her husband, Pierre, were jointly awarded the Nobel Prize in Physics for their pioneering work on radioactivity (a term she introduced). In 1911 Marie Curie won a second Nobel Prize, this time in chemistry for her discovery of the elements polonium and radium. 

We have already discussed the history of discovery of two natural radioactive elements, that is, uranium and thorium, in Chapter 4. These elements can fairly easily be found in minerals with chemical analysis since their content is sufficiently high. Other natural radioactive elements (polonium, radon, radium, actinium, and protactinium) are among the least abundant elements on Earth. Moreover, they exist in nature only because they are the products of radioactive transformations of uranium and thorium. 

Below readers will see for themselves how accurate were Mendeleev s predictions of the properties of a heavy analogue of tellurium. But these predictions had only an indirect effect on the history of polonium, if any. The discovery of polonium (and then radium) proved to be a significant milestone in the science of radioactivity and gave an impetus to its development. 

The introduction of spectral analysis made it possible to reveal the existence in natural objects of elements that could not be seen, felt or weighed. Now the history repeated itself but the role of indicator was played by radioactive radiaton, which could be measured with a radiometric technique. However, the results of the Curies were not faultless. They were wrong in suggesting a chemical similarity between polonium and bismuth. Even a brief look at the periodic system shows that the existence of a heavy analogue of bismuth is hardly possible. But one must not forget that the Curies did not extract pure metal, could not determine its relative atomic mass, and, finally, did not see differences in the spectra of polonium and bismuth. This is why they actually ignored a possible analogy between polonium and tellurium. 

The radiochemlstry of lead has a history almost as long as the history of radiochemlstry Itself. In 1099j three years after the discovery of radioactivity by Becquerel and only a year after the discovery of radium and polonium by the Curies,... 

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