History of Chemistry

B

New Fields of Chemistry

The most striking advances in chemistry in the 19th century were in the field of organic chemistry (see Chemistry, Organic). The structural theory, which gave a picture of how atoms were actually put together, was nonmathematical, but employed a logic of its own. It made possible the prediction and preparation of many new compounds, including a large number of important dyes, drugs, and explosives that gave rise to great chemical industries, especially in Germany.

At the same time, other branches of chemistry made their appearance. Stimulated by the advances in physics then being made, some chemists sought to apply mathematical methods to their science. Studies of reaction rates led to the development of kinetic theories that had value both for industry and for pure science. The recognition that heat was due to motion on the atomic scale, a kinetic phenomenon, led to the abandonment of the idea that heat was a specific substance (termed caloric) and initiated the study of chemical thermodynamics (see Thermodynamics). Continuation of electrochemical studies led the Swedish chemist Svante August Arrhenius to postulate the dissociation of salts in solution to form ions carrying electrical charges. Studies of the emission and absorption spectra of elements and compounds became important to both chemists and physicists (see Spectroscopy; Spectrum). In addition, fundamental research in colloid and photochemistry was begun. By the end of the 19th century, studies of this type were combined into the field known as physical chemistry (see Chemistry, Physical).

Inorganic chemistry also required organization. The number of new elements being discovered continued to grow, but no method of classification had been developed that could bring order to their reactions. The independent development of the periodic law by the Russian chemist Dmitry Ivanovich Mendeleyev in 1869 and the German chemist Julius Lothar Meyer in 1870 eliminated this confusion and indicated where new elements would be found and what their properties would be (see Elements, Chemical; Periodic Law).

At the end of the 19th century chemistry, like physics, seemed to have reached a stage in which no striking new fields remained to be developed. This view changed completely with the discovery of radioactivity. Chemical methods were used in isolating new elements such as radium, in the separation of the new class of substances known as isotopes, and in the synthesis and isolation of the new transuranium elements. The new picture of the actual structure of atoms obtained by physicists solved the old problem of chemical affinity and explained the relation between polar and nonpolar compounds. See Nuclear Chemistry.

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The other major advance for chemistry in the 20th century was the foundation of biochemistry. This began with the simple analysis of body fluids; methods were then rapidly developed for determining the nature and function of the most complex cell constituents. By midcentury biochemists had unraveled the genetic code and explained the function of the gene, the basis of all life; the field had grown so vast that its study had become a new science, molecular biology. See also Genetics.

C

Recent Research in Chemistry

Recent advances in biotechnology and materials science are helping to define the frontiers of chemical research. In biotechnology, sophisticated analytical instruments have made it possible to initiate an international effort to sequence the human genome. Success in this project will likely completely change the nature of such fields as molecular biology and medicine. Materials science, an interdisciplinary combination of physics, chemistry, and engineering, is guiding the design of advanced materials and devices. A recent example is the discovery of high-temperature superconductors, ceramic compounds that lose their resistance to the flow of electricity above 77K (-196° C/-321° F; see Superconductivity). Characterization of surfaces is being advanced by the invention of the scanning tunneling microscope, which can provide images of certain surfaces with atomic-scale resolution. See Microscope; Superconductivity.

Even in conventional fields of chemical research, new, more powerful analytical tools are providing unprecedented detail of chemicals and their reactions. For example, laser techniques are providing snapshots of gas-phase chemical reactions on the femtosecond (a millionth of a billionth of a second) time scale. From the soot produced by graphite electrodes has been isolated a new form of carbon, called buckminsterfullerene, that has the shape of a soccerball, and the chemical formula C₆₀. This compound and its chemistry have been characterized with astonishing rapidity using the vast array of analytical techniques currently available. Certain alkali metal salts of this compound have even been found to be superconducting.

D

The Chemical Industry

The growth of chemical industries and the training of professional chemists had an interestingly shared history. Until about 150 years ago chemists were not trained professionally. Chemistry was advanced by the work of those who were interested in the subject, but who made no systematic effort to train new workers in the field. Physicians and wealthy amateurs often hired assistants, only some of whom continued their masters' work.

Early in the 19th century, however, this haphazard system of chemical education changed. Many provincial universities were established in Germany, a country with a long tradition of research. A research center in chemistry was set up at Giessen by the German chemist Justus Liebig. This first teaching laboratory became so successful that it drew students from all over the world; other German universities soon followed.

A large group of young chemists was thus trained just at the time when chemical industries were beginning to exploit new discoveries. This exploitation had its start during the Industrial Revolution; the Leblanc process for the production of soda, for example—one of the first large-scale production processes—was developed in France in 1791 and was commercialized in England beginning in 1823. The laboratories of such growing industries were able to employ the newly trained chemistry students and also to use university professors as consultants. This interplay between the universities and the chemical industry benefited both of them, and the accompanying rapid growth of the organic chemical industry toward the end of the 19th century created the great German dye and pharmaceutical trusts that gave Germany scientific predominance in the field until World War I.

After the war, the German system was introduced into all the industrial nations of the world, and chemistry and chemical industries progressed even more rapidly. Among some of the more recent industrial developments, increasing use has been made of enzymatic reaction processes (see Enzyme), mainly because of the low costs and high yields that can be achieved. Industries are at present studying production methods using genetically altered microorganisms for industrial purposes (see Genetic Engineering).

E

Chemistry and Society

Chemistry has had an enormous influence on human life. In earlier periods chemical techniques were used to isolate useful natural products and to find new ways to employ them. In the 19th century techniques were developed for synthesizing completely new substances that were either better than the natural ones or could completely replace them more cheaply. As the complexity of synthesized compounds increased, wholly new materials with novel uses began to appear. Plastics and new textiles were developed, and new drugs conquered whole classes of disease. At the same time, what had been entirely separate sciences began to be drawn together. Physicists, biologists, and geologists had developed their own techniques and ways of looking at the world, but now it became evident that each science, in its own way, was the study of matter and its changes. Chemistry lay at the base of each of them. The resulting formation of such interscientific disciplines as geochemistry or biochemistry has stimulated all of the parent sciences.

The progress of science in recent years has been spectacular, although the benefits of this progress have not been without some corresponding liabilities. The most obvious dangers come from radioactive materials, with their potential for producing cancers in exposed individuals and mutations in their children. It has also become apparent that the accumulation in plant and animal cells of pesticides once thought harmless or of by-products from manufacturing processes often have damaging effects. These dangerous materials have been manufactured in enormous amounts and dispersed widely, and it has become the task of chemistry to discover the means by which these substances can be rendered harmless. This is one of the greatest challenges science will have to meet. See also Environment.

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