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GQI126 INVESTIGAÇÕES EM HISTÓRIA DA QUÍMICA Prof. Cleber Anconi DQI/UFLA Chemistry a volatileChemistry a volatile history (2): 18:43 – 48:26 � Participou do Congresso em Karlsruhe, na Alemanha. (1860). No evento, muitos cientistas discutiram pesos atômicos e pesos equivalentes dos elementos. Meyer investigtou a relação entre pesos atômicos e propriedades dos elementos quimicos. � Meyer procurou calcular o volume atômico dos elementos descobertos até então, 63 elementos. Em 1870, Meyer mostrou a relação de periodicidade entre volume atômico e massa atômica, traçando um gráfico destas propriedades. Após isso tentou mostrar a mesma relação de periodicidade de outras propriedades dos elementos, em função da massa atômica.atômica. � Praticamente na mesma época, Dmitri Mendeleiev conseguiu determinar uma relação de periodicidade de várias propriedades dos elementos em função da massa atômica. Entretanto, o seu trabalho recebeu maior destaque, pois, até mesmo, previa elementos desconhecidos na época. Dimitri Ivanovich Mendeleiev 1834-1907 Mendeleev's 1869 periodic table; note that his arrangement presents the periods vertically, and the groups horizontally. � European scientists in a short article in the german journal Zeitschrift fur Chemie (Journal of Chemistry) in 1869, which is on display. Mendeleev discovered the periodic law during the time he was engaged in writing the first edition of a chemistry textbook, Osnovy Khimii (Principles of Chemistry). Mendeleev based his periodic table on 'four aspects of matter' that revealed close relationships between certain chemical elements. These four aspects were isomorphism, the specific volumes of similar compounds or elements, the composition of compound salts, and relations among the atomic weights of elements. Since the periodic law was dependent upon the quantitative relation between atomic weight, as an independent variable, and an element's physical and chemical properties, Mendeleev in 1869 took up the problem of developing and entire 'natural system of elements'. He employed deduction to reach the boldest and most far-reaching logical consequences of the law that he had discovered, so that he might, by verification of these consequences, confirm the law itself. Among these consequences were predictions of the chemical properties of several unknown elements. Two of these elements, which we now know as gallium and germanium, were discovered in the 1870s and possessed almost exactly the properties Mendeleev had1870s and possessed almost exactly the properties Mendeleev had predicted for them. Mendeleev's periodic table is one of the most important chemical discoveries of the nineteenth century; it remains today a central unifying principle in the science of chemistry. The first edition of Osnovy Khimii (shown here) is exceedingly rare as only about six copies exist in the US. The copy on display is unusual in that volume 2 is evidently a previously unrecorded first issue. It consists of only the first half of volume 2, the title page is green instead of the usual white, and the publication date is 1870 instead of the usual 1871. The title page says that this is the third part of Osnovy Khimii, the first two parts evidently corresponding to what normally is issued as volume 1. This part 3 is complete, as judged from the fact that the number of illustrations indicated on the title page agrees with the number that appear in the text. The large folding table, which was included in the 1871 issue of the full volume 2, is missing in this present copy. Presumably, the folding table, which consists of an improved version of the 1869 periodic table that appears in volume 1, was not devised until after 1870. In crystallography, goniometers are used for measuring angles between crystal faces. They are also used in X-ray diffraction to rotate the samples. The groundbreaking investigations of physicist Max von Laue and cohorts into the atomic structure of crystals in 1912 involved a goniometer. Periodic Table of Chemical Elements mosaic near Mendeleev monument in St Petersburg. This table is based on the last 8th edition of Mendeleev's book "Principles of Chemistry" (1906). Red elements were discovered in the lifetime of the scientist, blue elements - from 1907 to 1934. The total area is 69 sq.m Osnovy Khimii (Principles of Chemistry)
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