History of the Electron

A major objective of this book is to evaluate the reported values of molecular electron affinities and their errors and to assign them to specific states. Prior to 1970 the magnetron and ECD methods were used to measure the majority of gas phase molecular electron affinities. An extensive compilation of unevaluated experimental, empirical, and theoretical electron affinities of atoms, molecules, and radicals was published before 1990 [9]. The electron affinities measured in the gas phase are now available on the Internet but have not been evaluated [26]. The molecular Ea in this list is defined and evaluated in Appendix IV. Values that are significantly lower than the selected values will be assigned to excited states. Semi-empirical calculations and the CURES-EC technique support these assignments. Unpublished electron affinities and updated electron affinities from charge transfer complex data and half-wave reduction potentials are given in Appendix IV. 

The chemical power of a current of electricity exists in direct proportion to the absolute quantity of electricity that passes through it. 

The equivalent weight of bodies is simply those quantities that contain equal quantities of electricity. 

Scottish physicist James Clerk Maxwell, who developed the theory of electricity and magnetism in the late 1800s, proposed that Faraday s laws required that one molecule of positive and negative electricity is involved in electrolysis. Irish physicist George Johnstone Stoney believed in this molecule of electricity and set out to measure the definite quantity of electricity, called el. He suggested that if this unit of electricity was adopted, it would represent a very important step in our study of molecular phenomena. In 1891 Stoney referred to these charges as electrons. The controversy of the day then revolved around whether these electrons were waves or particles. 

The relationships to electromagnetic waves postulated by the German physicist Heinrich Rudoph Hertz led to the work of the English physicist Sir Joseph John Thomson in 1897, which is often linked to the actual discovery of the electron [26]. The measurement of the e/m and m of the corpuscles called electrons by Thompson settled this controversy. Electrons were at least particles, but other studies suggested that they were also electromagnetic radiation. Thompson described his conclusions as follows  

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Whether or not, or to what extent, Thomson discovered the electron has been the focus of much historical research. See various articles in J. Buchwald, A.Warwick (eds.). Histories of the Electron The Birth of Microphysics, MIT Press, Cambridge, MA, 2001. 

Gavroglu, K. 2001. The physicists electron and its appropriation by the chemists. In Histories of the electron. The birth of microphysics, ed. J. Buchwald and A. Warwick, 363-400. Cambridge, MA MIT Press. 

Physical Properties. Most of the physical properties discussed herein depend on the direction of measurement as compared to the bedding plane of the coal. Additionally, these properties vary according to the history of the piece of coal. Properties also vary between pieces because of coal s britde nature and the crack and pore stmcture. One example concerns electrical conductivity. Absolute values of coal sample specific conductivity are not easy to determine. A more characteristic value is the energy gap for transfer of electrons between molecules, which is deterrnined by a series of measurements over a range of temperatures and is unaffected by the presence of cracks. The velocity of sound is also dependent on continuity in the coal. 

The elemental composition of the fish otoliths is a potential source of the useful information to recreate environment history of the individual fish in some of the species. In-depth study of the chemical composition of the otolith center (formed eaidy in fish life) and otolith edge (formed later in fish life) ensures chronological and environmental information stored in the otoliths [1]. This infoiTnation may be achieved by X-ray electron probe microanalysis (EPMA). EPMA is the analytical method to determine the elemental composition of different otolith s parts, their sizes varying from ten up to some tens of microns. 

The current-voltage and luminance-voltage characteristics of a state of the art polymer LED [3] are shown in Figure 11-2. The luminance of this device is roughly 650 cd/m2 at 4 V and the luminous efficiency can reach 2 lm/W. This luminance is more than adequate for display purposes. For comparison, the luminance of the white display on a color cathode ray tube is about 500 cd/m2l5J. The luminous efficiency, 2 lm/W, is comparable to other emissive electronic display technologies [5], The device structure of this state of the art LED is similar to the first device although a modified polymer and different metallic contacts are used to improve the efficiency and stability of the diode. Reference [2] provides a review of the history of the development of polymer LEDs. 

Quantum Mechanics has been the most spectacularly successful theory in the history of science. As is often mentioned the accuracy to which the anomalous magnetic moment of the electron can be calculated is a staggering nine decimal places. Quantum Mechanics has revolutionized the study of radiation and matter since its inception just over one hundred years ago. The impact of the theoiy has been felt in... 

Wolfgang Pauli is well recognized as an outstanding theoretical physicist, famous for his formulation of the two-valuedness of the electron spin, for the exclusion principle, and for his prediction of the neutrino. Less well known is the fact that Pauli spent a lot of time in different avenues of human experience and scholarship, ranging over fields such as the history of ideas, philosophy, religion, alchemy and Jung s psychology. Pauli s... 

The present Proceedings mark a milestone in the history of the laser as well as a milestone in the International School of Quantum Electronics. 

The next significant development in the history of the geometric phase is due to Mead and Truhlar [10]. The early workers [1-3] concentrated mainly on the spectroscopic consequences of localized non-adiabatic coupling between the upper and lower adiabatic electronic eigenstates, while one now speaks... 

The shape function had a role in theoretical chemistry and physics long before it was named by Parr and Bartolotti. For example, in x-ray measurements of the electron density, what one actually measures is the shape function—the relative abundance of electrons at different locations in the molecule. Determining the actual electron density requires calibration to a standard with known electron density. On the theoretical side, the shape function appears early in the history of Thomas-Fermi theory. For example, the Majorana-Fermi-Amaldi approximation to the exchange potential is just [3,4]... 

Lowry praised the 1916 memoir of the American chemist Lewis as a "turning point in the history of chemistry" with its "plausible theory" of the electronic origin of the different types of chemical affinity and a clear differentiation between two kinds of valence, ionic and covalent. It is customary in mineral chemistry, he said, to consider reactions that occur between ions to be instantaneous, without attaching any importance to ionization in organic chemistry, except for the formation of salts from organic acids. 

A common language unifies a community of practitioners, at the same time that it sets them apart from other communities. As the chemist Mayer wrote Lewis about Slater s lecture at the Baltimore meeting of the American Physical Society, the talk of tetrahedral axes and coupling sounded so familiar that "I felt much at home " 15 In this regard, the invention of the phrase "resonance hybrid" should be remarked as a stroke of genius. No term could better have expressed the union of the natural philosophy tradition ("resonance") and the natural history tradition ("hybrid") in the theory of the electronic constitution of benzene. Both physicists and chemists felt at home. 

The discovery of the rare earth elements provide a long history of almost two hundred years of trial and error in the claims of element discovery starting before the time of Dalton s theory of the atom and determination of atomic weight values, Mendeleev s periodic table, the advent of optical spectroscopy, Bohr s theory of the electronic structure of atoms and Moseley s x-ray detection method for atomic number determination. The fact that the similarity in the chemical properties of the rare earth elements make them especially difficult to chemically isolate led to a situation where many mixtures of elements were being mistaken for elemental species. As a result, atomic weight values were not nearly as useful because the lack of separation meant that additional elements would still be present within an oxide and lead to inaccurate atomic weight values. Very pure rare earth samples did not become a reality until the mid twentieth century. 

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