Hypothesis atomic

During the early years of physieal ehemistry, Ostwald did not believe in the existence of atoms... and yet he was somehow ineluded in the wild army of ionists. He was resolute in his scepticism and in the 1890s he sustained an obscure theory of energetics to take the place of the atomic hypothesis. How ions could be formed in a solution containing no atoms was not altogether clear. Finally, in 1905, when Einstein had shown in rigorous detail how the Brownian motion studied by Perrin could be interpreted in terms of the collision of dust motes with moving molecules (Chapter 3, Section 3.1.1), Ostwald relented and publicly embraced the existence of atoms. 

This chapter is entitled Precursors of Materials Science and the foregoing major Sections have focused on the atomic hypothesis, crystallography, phase equilibria and microstructure, which I have presented as the main supports that made possible the emergence of modern materials. science. In what follows, some other fields of study that made substantial contributions are more brielly discussed. It should be remembered that this is in no way a le.xihnok, my task is not to explain the detailed nature of various phenomena and entitities, but only to outline how they came to be invented or recognised and how they have contributed to the edifice of modern materials science. The reader may well think that I have paid too much attention, up to now, to metals that was inevitable, but I shall do my best to redress the balance in due course. 

A striking example of the importance of narrowing the focus in research, which is what the concept of the parepisteme really implies, is the episode (retailed in Chapter 3, Section 3.1.1) of Eilhard Mitscherlich s research, in 1818, on the crystal forms of potassium phosphate and potassium arsenate, which led him, quite unexpectedly, to the discovery of isomorphism in crystal species and that, in turn, provided heavyweight evidence in favour of the then disputed atomic hypothesis. As so often happens, the general insight comes from the highly specific observation. 

Atom-hiille, /, atomic envelope or sheath (total electrons surrounding the nucleus). -hy-potbese, /. atomic hypothesis. 

Once they have detected patterns, scientists develop hypotheses, possible explanations of the laws—or the observations—in terms of more fundamental concepts. Observation requires careful attention to detail, but the development of a hypothesis requires insight, imagination, and creativity. In 1807, John Dalton interpreted experimental results to propose the hypothesis that matter consists of atoms. Although Dalton could not see individual atoms, he was able to imagine them and formulate his atomic hypothesis. Dalton s hypothesis was a monumental insight that helped others understand the world in a new way. The process of scientific discovery never stops. With luck and application, you may acquire that kind of insight as you read through this text, and one day you may make your own extraordinary hypotheses. 

The postulates of Dalton s atomic hypothesis are described in Section B. 

B.2 (a) Which part of Dalton s atomic hypothesis has been disproved by experiments (b) Summarize the evidence disproving this hypothesis. 

Atoms Humbug Rarely does a major new eoneept receive unanimous acceptance. Despite the atomie theory s impact, several major seientists denied the existence of atoms for another eentury. In 1877, Adolf Kolbe, an eminent organic chemisf said [Dalton s atoms are]. .. no more than stupid hallucinations. .. mere table-tapping and supernatural explanations. The influential physicist Ernst Mach believed that scientists should look at facts, not hypothetical entities such as atoms. It was not until 1908 that the famous chemist and outspoken opponent of atomism Wilhelm Ostwald wrote, I am now convinced [by recent] experimental evidence of the discrete or grained nature of matter, which the atomic hypothesis sought in vain for hundreds and thousands of years. (p.45)... 

If, in some cataclysm, all of scientific knowledge were to be destroyed, and only one sentence passed on to the next generations of creatures, what statement would contain the most information in the fewest words I believe it is the atomic hypothesis (or the atomic/act, or whatever you wish to call it) that all things are made of atoms—little particles that move around in perpetual... 

All compounds, from the simple ones such as water and ammonia to the most complex, are held together by chemical bonds. All chemical bonds—from purely covalent to strongly ionic—act the way they do because of the nature of the atoms that form the bonds. Our knowledge of those atoms is at the heart of the science of chemistry. Understanding Richard Feynmans little particles has enabled mankind to manage the natural world to suit its needs. Feynman was undoubtedly correct when he said that the atomic hypothesis (or the atomic fact, or whatever you wish to call it) is the most concise and important summary of scientific knowledge produced by mankind. And it is crucial that every generation passes it on to the next. 

John Dalton s Atomic hypothesis. J. Fraunhofer locates and names Fraunhofer lines A...L in solar spectrum. About the same time, Herschel discovers infrared radiation from the Sun. 

William Prout s composite atoms hypothesis. G. Kirchhoff and R. Bunsen discover spectral analysis and significance of Fraunhofer lines Kirchhoff s law. 

Elisabeth Crawford, "Arrhenius, the Atomic Hypothesis, and the 1908 Nobel Prizes in Physics and Chemistry," Isis 75 (1984) 503522. 

On the controversial question of the atomic hypothesis, Edward Frankland was more circumspect ... 

The question whether atoms exist or not.. . belongs rather to metaphysics. In chemistry we have only to decide whether the assumption of atoms is an hypothesis adapted to the explanation of chemical phenomena. . . [and] whether a further development of the atomic hypothesis promises to advance our knowledge of the mechanisms of chemical phenomena.. .. I rather expect that we shall some day find, for what we now call atoms, a mathematico-mechanical explanation, which will render an account of atomic weight, of atomicity, and of numerous other properties of the so-called atoms. 50... 

While divided over the atomic hypothesis, which many chemists deemed metaphysical rather than physical, the entire chemical framework of the nine-... 

Hypothesis," Transactions of the Cambridge Philosophical Society 14 (1887) 71120 "On a Certain Atomic Hypothesis," Proceedings of the London Mathematical Society 20 (1889) 3863 and "Ether Squirts. Being an Attempt to Specialize the Form of Ether Motion which Forms an Atom in a Theory Propounded in Former Papers." American Journal of Mathematics 13 (1891) 309362. 

Volume 3 explains the systems of molecular and atomic weight, valences, the atomic theory, the system of classification of the elements, and the laws of chemical equilibrium. Here we find Lespieau s view that the goal of chemistry is the formule developee, not the formule brute, and that the atomic hypothesis gives us a striking interpretation and creates a language that is now adopted by all chemists, even those who reject the hypothesis of an indivisible primordial particle.30... 

Lespieau s view was that organic chemistry must make use of physical methods and of physical chemistry and that the experimental work of Graham, Williamson, Wurtz, and, more recently, Raoult had confirmed the superiority of the atomic hypothesis over chemical equivalents. As for the meaning of the constitutional (structural, developed) formula,... 

Most chemists immediately utilized the compositional relationships derived from the atomic hypothesis, but for most of the century they continued to dispute the ontological reality of the atoms that rationalized their useful consequences. Even those most doubtful of the reality of the atom found its operational utility indispensible. Humphry Davy was expressing composition by the relative numbers of proportions by i8io, and William Wollaston attempted a calculus of chemical equivalents in 1814. Jons Jakob Berzelius undertook a systematic determination of the most accurate values to assign each of the atomic weights, publishing his first list in 1813. 

Although it was Daltons atomic hypothesis that first achieved the idealized goal of a true chemical calculus, the effort to acquire the requisite precision of data called for by Lavoisier had made substantial progress before 1808. Indeed without that accumulation of the empirical data, Daltons hypothesis would have carried no persuasion at all in a climate still dominated by an inductivist epistemology. 

John Dalton (1766-1844) lived and worked most of his life in Manchester, and he was a mainstay of that city s Literary and Philosophical Society. He had a life-long interest in the earth s atmosphere. Indeed, it was this interest that led him to study gases, out of which study grew his atomic hypothesis (2). His experiments on gases also led to a result now known as Dalton s law of partial pressures (5). Dalton s name is also linked to color blindness, sometimes called daltonism, a condition he described from firsthand experience. 

The laws of definite and multiple proportions are also associated with Dalton, for they can be explained by his atomic hypothesis. The law of definite proportions or of constant composition had previously been proposed in the work of Jeremias Richter and Joseph-Louis Proust. The law of multiple proportions came to be regarded as an empirical law quite independent of its relation to the atomic hypothesis or perhaps as an empirical law that inspired the atomic hypothesis however, Roscoe and Harden have shown that in Dalton s mind it was a testable prediction which followed from the atomic hypothesis 4). 

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