Discovery of isotopes

Discovery of a nitrogen isotope N by S. M. Naudd following the discovery of isotopes of O and C by others earlier in the same year. 

Electrons. If the discovery of isotopes threatened ro undermine the periodic system, the discovery of the electron explained many of the periodic properties on which the table was based. J. J. Thomson attempted to explain the periodic system by postulating rings of electrons embedded in the positive charge that made up his phim pudding model of the atom. Thomson s model was quickly superseded by more sophisticated and elaborate mod-... 

However, an important development within atomic physics, namely the discovery of isotopy in the 1910s, led some philosophically minded chemists to reexamine Mendeleev s distinction and to rehabilitate it in a modified form. With the rapid discovery of isotopes it began to seem as though there were far more "elements" than the 90 or so which were displayed on periodic tables at the time. The work of Soddy [14], in particular, served to clarify the situation, and one that had been anticipated by Crookes,... 

But what would become of Mendeleev s periodic system which now seemed to consist of 300 or so "elements" To some chemists, the discovery of isotopes implied the end of the periodic system as it was known.3 These chemists suggested that it would be necessary to consider the individual new isotopes as the new "elements." But the chemist Paneth adopted a less reductionist approach, arguing that the periodic table of the familiar chemical elements should be retained because it dealt with the "elements" that were of interest to chemists. A justification for this view was provided by the fact that, with a few exceptions, the chemical properties of isotopes of the same element are indistinguishable.4 Moreover, Paneth appealed to Mendeleev s distinction between the two senses of the concept of an "element" in order to provide a philosophical rationale for the retention of the chemist s periodic table. Paneth argued that the discovery of isotopes of the elements represents the discovery of new elements as simple substances, whereas periodic... 

Abstract A brief introduction deals with the time period from Dalton to the discovery of isotopes by Soddy and Fajans in the early twentieth century which was soon followed by the invention of the mass spectrograph (1922). The next section covers the period from 1922 to the discovery of deuterium by Urey and his colleagues. It includes a discussion of isotope effects in spectroscopy, particularly band spectra of diatomic molecules, and also discusses the discovery of the important stable isotopes in the second row of the periodic table. It ends with the discovery of deuterium, probably the most popular isotope for isotope effect studies. The chapter ends with a short description of the apparatus of theory and experimentation available for isotope effect work at the time of the discovery of deuterium. 

From the Discovery of Isotopes through the Invention of the Mass Spectrograph by Aston... 

This period also focuses on the discovery of isotopes of light weight elements some of which have such low natural abundance that they could not be detected by the mass spectrographs available in the early part of the twentieth century, but which may be very desirable for study because isotope effects involving lightweight elements tend to be much larger than those for heavier elements. A prime example is the discovery of deuterium in 1932, one of the major events in isotope chemistry during this time period. 

The Discovery of Isotopes of Carbon, Nitrogen, and Oxygen, and Hydrogen... 

Francis W Aston Great Britain mass spectrography and discovery of isotopes... 

Romer, A. Radiochemistry and the Discovery of Isotopes, Dover, New York, 1970. An intriguing view of the beginning of nuclear chemistry. 

Rayner-Canham, M. F. and Rayner-Canham, G. W. (2000). Stefanie Horovitz, Ellen Gleditsch, Ada Hitchins and the discovery of isotopes. Bulletin for the History of Chemistry 25(2) 103-108. 

Two other, partially successful models to account for elemental periodicity, were proposed before and forgotten after the advent of quantum theory. An anonymous proposal, later ascribed to Prout, was based on the assumption that all atoms are composites of hydrogen. The purpose of this proposal was to account for the statistically improbable distribution of relative atomic weights, close to integer values. Following the discovery of isotopes Prout s hypothesis gained some new respectability, but it has never been fully exploited. Another theory was summarized by its author [20] in the statement ... 

Since conception over 100 years ago, MS has become an important analytical and research tool with diverse applications ranging from astronomical study of the solar system to materials analysis and process monitoring in chemical, oil and pharmaceutical industries. Use of MS has led to very many scientific breakthroughs including the discovery of isotopes, accurate determination of atomic mass, and the characterization of biomolecular structure. Indeed, MS is now a fundamental technique employed in pharmacology, toxicology and other biological, environmental and biomedical sciences. 

The discovery of isotopes was made by Frederick Soddy in 1910. Earlier, Soddy had worked with Ernest Rutherford at McGill University, where they laid out the basis for understanding radioactivity in their paper The Cause and Nature of Radioactivity. From Montreal, Soddy went first to London for one... 

Soddy s discovery of isotopes put Prout s provocative idea that hydrogen was the basic building block of the chemical elements into the inactive archives of science history. The observed weights of the chemical elements are determined by their isotopic composition, which failed to be multiples of hydrogen, as Prout believed it would be. The atomic weight of oxygen, for example, is 15.9994, and that of chlorine is 35.453. 

Prout s hypothesis was revived by the discovery of isotopes thus chlorine con sists of two natural isotopes and CP" , and boron of two isotopes B and in each case with nearly integral atomic weights and present in such relative amounts as to give the chemical atomic weight. It is now seen that Prout s idea e ntained an element of truth. 

The discovery of isotopes has caused the ideas about constancy of composition to be revised in an obvious way only if the distribution of isotopes were uniform would substances show constant composition by weight. It has been found by experiment that for most elements the natural distribution of isotopes is uniform to within experimental error. 

Tfiis physical apparatus has become useful in several ways in attacking chemical problems. Its principal uses have been for the discovery of isotopes and the determination of atomic weights. The importance of these uses justifies a brief discussion of the apparatus and the way it works. 

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