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Chemistry I
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Joseph Priestly (1733-1804) was a great experimental chemist, but in his own mind more importantly a minister, theologian, and educator. He was persecuted for his political and religious views to the point that he had to leave England and emigrate to the United States, where he spent the last ten years of his life. His important work with gases included the preparation of oxygen, the discovery of ammonia, sulfur dioxide, carbon monoxide, nitric oxide, and hydrogen sulfide. |
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Antoine Laurent Lavoisier (1743-94)(Detail) was a French chemist whose work in combustion showed that substances gain weight when burned, and the air they burn in loses weight, now known as the law of conservation of mass. He stated that air was composed of two gases, one of which supported combustion (Priestley's oxygen) and the other of which was inert, nitrogen. He made a list of elements then known and started the practice to name compounds after their constituent parts. His life was cut short by the guillotine during the French Revolution. |
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Joseph Louis Gay-Lussac (1778-1850) studied the properties of gases. Hot air ballooning was becoming a popular activity and Gay-Lussac availed himself of the new technology. He found, after balloon ascents, that the composition of the air at high altitudes is the same as at sea level, and that the earth's magnetic field remains constant with altitude. He also discovered that different gases expand by the same amount for the same rise in temperature (Gay-Lussac's Law). |
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Amedeo Avogadro (1776-1856) took Gay-Lussac's Law one step further. He stated one of the basic concepts of modern chemistry in his Law, that equal volumes of gases at the same temperature and pressure contain equal numbers of molecules. The very small print and the crowded text on this Italian commemorative (Detail) may suggest a large (Avogadro's) number of molecules confined to some small space. |
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Jons Jakob Berzelius (1779-1848), a Swedish chemist, devised the symbolic language of chemistry, designating each element by the first letter(s) of its Latin name. He measured atomic weights and advanced the idea of radicals, and was the influential author of a textbook and annual reviews of chemical progress. |
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Johan Gadolin (1760-1852) was a Finnish chemist who in the late 18th century experimented with a mineral from Ytterby, Sweden, which contained new, uncommon oxides, or "earths." Over the next century other investigators were able to identify more than a dozen unknown elements contained in this rare earth, which were called lanthanides. Lecoq de Boisbaudran, himself the discoverer of gallium, named one of the rare earths to honor Gadolin: this was gadolinium. |
Justus von Liebig (1803-1873) worked in quantitative organic analysis and was the great chemistry teacher of the 19th century. He founded a laboratory in Giessen where research methods were taught. His research into chemical fertilizers earns him a spot on the East German stamp on the right. |
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Friedrich Wohler (1800-1882) was a German chemist who first synthesized a natural product, urea. As shown on the stamp, ammonium cyanate decomposes when heated into urea. Wohler originated many analytical procedures, isolating boron and silicon, among others. A collaborator of Liebig's, he also edited Annalen der Chemie. |
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 Friedrich
August Kekule von Stradonitz (1829-1896) was a German chemist who investigated
chemical bonds, suggested that carbon was tetravalent, and proposed a
ring structure for benzene. He introduced the convention of using the
term organic chemistry generally for the chemistry of carbon compounds;
this term had previously been reserved for compounds of living matter. |
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