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1、 Reading Materials for Chemistry English Periodic Table Digested from Chemical & Chemical Engineering News (80th Anniversary Issue), Vol. 81, No. 36, 2003, Sept. 8. Edited by X. Lu 1 Introduction The Periodic Table is natures rosetta stone. To the uninitiated, its just 100-plus numbered boxes, each
2、containing one or two letters, arranged with an odd, skewed symmetry. To chemists, however, the periodic table reveals the organizing principles of matter, which is to say, the organizing principles of chemistry. At a fundamental level, all of chemistry is contained in the periodic table. Thats not
3、to say, of course, that all of chemistry is obvious from the periodic table. Far from it. But the structure of the table reflects the electronic structure of the elements, and hence their chemical properties and behavior. Perhaps it would be more appropriate to say that all of chemistry starts with
4、the periodic table. What has always struck me as remarkable about Dmitry Mendeleyevs discovery in 1869 of a way to arrange the elements known at that time into a meaningful and predictive periodic table is that he accomplished it without any knowledge of the structure of atoms. There are no atomic n
5、umbers on Mendeleyevs periodic table, only atomic weights and the groupings of elements based on their known properties. More than 30 years would pass before J. J. Thomson (who discovered the electron) suggested that the electronic configuration of atoms might account for the periodicity of the elem
6、ents, and more than 40 years would pass before atomic numbers were recognized as the basis for ordering the elements. Indeed, as John Emsley notes in his invaluable book, “Natures Building Blocks: An AZ Guide to the Elements,” Mendeleyev never accepted that electrons came from atoms because he was c
7、onvinced that atoms were indivisible. No matter. Mendeleyevs brilliant insight propelled chemistry into the 20th century. New elements were discovered that filled in the holes Mendeleyev left in his table, and their atomic weights and chemical properties corresponded with remarkable accuracy to Mend
8、eleyevs predictions. And as the revolution in chemistry and physics unfolded in the early decades of the 20th century, most of the discoveries about the structure of atoms, their properties, and how they interact with each other made perfect sense in light of the periodic table. The periodic table i
9、s so central to chemistry that it seemed natural to devote a special issue to it and the elements that compose it as we celebrate C&ENs 80th anniversary. The 89 essays are delightfully varied. We hope they will give you a new perspective on and appreciation of the building blocks of our science. 2 H
10、YDROGEN JUDITH KLINMAN, UNIVERSITY OF CALIFORNIA, BERKELEY To be the number one-not to mention the most abundant and lightest-element on the periodic table is a weighty responsibility. But hydrogen does not disappoint. Its role in the universe is indisputable, but for me its attraction lies in its t
11、wo long-lived isotopes: one stable, deuterium (D), and one radioactive, tritium (T). In fact, I cant imagine the emergence of modern chemistry and biochemistry without the benefit of these isotopes. My first exploration of deuterium was as a graduate student with Edward Thornton, when we used solven
12、t D 2 O to examine mechanisms of carbonyl reactivity in the condensed phase. But biology beckoned, and the application of hydrogen isotopes to biochemical processes proved irresistible. Working subsequently with Irwin Rose as a postdoctoral researcher, I used enzymes to prepare methyl groups that we
13、re chiral by virtue of the presence of H, D, and T. The key to unlocking the cryptic stereochemistry for the production and utilization of chiral methyl groups by metabolic enzymes lay with the difference in reaction rate between H and D. Theories of kinetic isotope effects had been advanced in the
14、preceding years. These attributed isotopic differences in rate to differences in the energy of the ground-state stretching modes of the labeled bonds, which were recognized as arising solely from the altered masses of the isotopes. Eureka-with the expectation that the potential energy surface of the
15、 labeled bond would be unaffected-biochemists had found the long-awaited nonperturbing probe with which to analyze the nature of catalysis in enzymatic reactions. A decade and a half of exciting activity followed. Suddenly, it was possible to dissect enzyme reactions into their individual steps, lea
16、rning in the process how enzymes alter the reaction-barrier height together with the internal thermodynamics for the interconversion of bound reactants and products. Around the mid-1980s, scientists began to realize that all was not as it had seemed-experimental anomalies indicated breakdowns in classical theories of kinetic hydrogen isotope effects. This was met with a healthy blend of curiosity and resistan
