HEVESI (Hevesy), Georg (Gyö²rgy) de( Hungarian-Swedish chemist, Nobel Prize in Chemistry, 1943)
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Biography HEVESI (Hevesy), Georg (Gyö²rgy) de
August 1, 1885, Mr.. - July 5, 1966
. Hungarian-Swedish chemist, Georg (Gyö²rgy) de Hevesy was born in Budapest (Austria-Hungary) and was one of eight children of Louis de Hevesy, . Court Chair, . steward of mining companies and a few family farms, . and Eugenia (nee Shlosberger) de Hevesy,
. In 1903, Mr.. H. graduated from high school piaristskogo Order in Budapest, where he devoted much attention to mathematics and physics. During the year he attended the Budapest University. Then, having decided to become a chemical engineer, he joined the Berlin University of Technology (equivalent to a technical college). Forced to move to a warmer climate zone, as a few months of school, he fell ill with pneumonia, X. transferred to the University of Freiburg, located in southern Germany, where the physical chemistry became his main subject.
In 1908, Mr.. after the submission of the thesis on the interaction of metallic sodium with molten sodium hydroxide, he received his doctorate.
. After that he worked for two years in Zurich Federal Institute of Technology under the leadership of Richard Lorenz, a recognized authority in the chemistry of molten salts
. Zurich X. attended lectures by Albert Einstein, who in 1909. worked in a nearby university, and even visited his laboratory. In 1910,. H. spent three months in Karlsruhe in Germany, engaged in joint research with Fritz Haber, and then received a prestigious scholarship for research in the laboratory of Ernest Rutherford at Manchester University in England. There had friendships with Niels Bohr, lifelong. At the suggestion of Rutherford X. investigated the chemical properties of actinium recently discovered radioactive chemical element.
. At this time, Rutherford was working on his concept of atomic structure as a dense nucleus containing almost the entire mass of the atom and surrounded by much lighter electrons
. Although knowledge of the radioactive elements were still meager, however it was known that their atoms have unstable nuclei which disintegrate under the influence of radiation. It was also aware that they have different and characteristic for each element of the average decay rate. Velocity is expressed in the values of half-time - time in which half of the initial nucleus undergoes radioactive decay. The problem, posed in front of H. Rutherford, has been intractable because the half-life of actinium was equal to only three seconds. However, it has provided X. favorable opportunity to get acquainted with the methodology of studies of short-lived substances and later identified his interest in the electrochemistry of radioactive elements.
After the study actinium Rutherford asked X. identify radioactive radium-D, one of the so-called daughter products of decay of radium, a large quantity of lead obtained from the laboratory of the Austrian Government. Rutherford was very much like to investigate radiation daughter products of radium, but do not succeeded, because in too large quantities of lead contained virtually grain of radium-D. Although X. not succeeded in obtaining a radium-D, he came to mind a great idea. Based on the fact that radium-D can not be separated from the lead because of their chemical similarity, it is assumed that radium-D may be added to the lead as a detectable marker or label. Behavior of lead in chemical reactions, thus, can be traced by measuring the radiation of his tags. When you visit the Vienna Institute for the study of radium X. learned that Frederick Adolph Panet, assistant of the Institute, also unsuccessfully tried to extract radium-D from lead. After an exchange of letters, they decided to work together, and in 1913. H. to Vienna. He and Panet vekore proved the value of labeling with radium-D of lead, allowing them to measure extremely small amounts of this element (three times less compared with other tests). Labeling it possible to determine the low solubility of lead and its compounds in water and other solvents, as well as the diffusion of atoms in a piece of lead.
In 1913, Mr.. Research Frederick Soddy, Francis Y; Aston and Dzh.Dzh. Thomson demonstrated the existence of isotopes - atoms of the same element but with different weights. Chemical element characterized by the number of protons (positively charged particles) in the nuclei of atoms of this element, which must equal the number of electrons (negatively charged particles orbiting the nucleus of an atom is electrically neutral. Because chemical reactions occur changing only the electrons and atoms of the same element, regardless of differences in the atomic weights have the same number of electrons, isotopes of an element have the same chemical properties. It became clear that the radioactive radium-D and inert lead is indivisible by chemical means, as they are isotopes of the same element and, hence, are chemically identical. Collaboration X. Paneth and to identify the electrical properties of radium-D showed that it is identical to the lead on this parameter.
. Differences in atomic weight between the different isotopes of the same elements were also explained in 1932 when James Chadwick discovered neutrons
. Neutrons have almost the same weight with the protons, but do not carry a charge, so they increase the atomic weight, but do not affect the chemical properties.
Soon after his return in 1913. in Manchester to continue the study of radioactive ions (charged atoms that have an excess or deficiency of electrons to neutralize the charge of the proton nucleus) X. received an invitation to a permanent job at Oxford University, but the beginning of World War I forced him in 1914. return to Vienna. Two years later he was called up for military service. During the next year it is - a technical controller at the electrochemical factory near Budapest, and a year later - on the Hungarian state copper plants in the Carpathians. At the end of the war he became a professor of physical chemistry, and then the Acting Director of the 2 nd Physics Institute, University of Budapest. But in 1919. in connection with the beginning of the revolution in Hungary, he immediately goes to the Bohr Institute for Theoretical Physics in Copenhagen. After Bohr agreed to provide X. long-term operation, he returned to Hungary to finish their experiments there. These studies have shown that in mixed solutions containing chloride, lead nitrate, lead and other salts of lead, the atoms can be exchanged for one another, whereas in svinetsorganicheskih compounds such exchange occurs.
. In 1920, Mr.
. H. finally moved to the Institute to Bor. There he was a lot of trouble, having achieved the separation of isotopes of mercury and chlorine, using differences in their boiling point and the rate of diffusion in the physical properties that vary with the atomic weight. He also tried to open the elusive element under the number 72. Although this 72-electronic element has not yet been found, its chemical properties theoretically already predicted. H. expect to find in the minerals, enriched with zirconium, the small number of elements which, apparently, was supposed to be chemically similar to element 72. With Dirk Koester, a Danish experimenter Research X-rays, X. discovered a new element and named it hafnium from the Latin name of Copenhagen. After studying the chemical properties of hafnium X. returned to the issue of separation of isotopes.
Although X. with great interest the work in Copenhagen, especially in conjunction with Bohr in 1926, Mr.. He has served as professor of physical chemistry at the University of Freiburg, where he had left many friends and colleagues. In Freiburg, he spent X-ray analysis of minerals, watching the glow after the bombing of the powerful beams of X-rays. He and his colleagues have also used radioactive isotopes to study chemical and biological systems.
When Hitler became in 1933. Chancellor of Germany, X. resigned, but remained at Freiburg for one more year to help their students complete their dissertations. In 1934, Mr.. He returned to Copenhagen, the Institute of Theoretical Physics, where he was granted the laboratory, which also could work and his students.
Even in Freiburg X. began biological research using heavy water as the labeled molecules. Heavy water - is hydrogen oxide, or H2O, in which ordinary hydrogen is replaced by a heavier isotope of hydrogen, deuterium (H2O Á?? D2O), open Harold Clayton Urey in 1932. The nucleus of deuterium, or heavy hydrogen, consists of a proton and neutron. The presence of deuterium, . stable isotope of hydrogen, . reliably identify the density of water, . than by measuring the radioactivity, . Although heavy water can also contain a fraction of the third isotope of hydrogen, . tritium (two neutrons in the nucleus), . which radioactive,
. H. and Urey had known each other since 1923, Mr.. by Bohr Institute. Having already from Urey several liters of water containing 0.6% heavy water, X. measured the exchange of water molecules between the goldfish and the environment in the aquarium, as well as the water content in the human body and the duration of the water in the body. This study was interrupted due to his move to Copenhagen. Although a few years he continued to work with heavy water, its planned studies in Copenhagen were abruptly changed by the opening of Frederic Joliot-Curie and Irene Joliot-Curie of artificial radioactivity in 1934
First use of X. radioactive label was limited because of the scarcity of suitable set of isotopes occurring in nature. Now, when it became possible to create artificially radioactive isotopes, the choice has expanded. Selected as the first radioactive isotope of phosphorus, he measured the rate of accumulation and distribution of phosphorus in the bones. Follow his research concerned the penetration of potassium in red blood cells, . accumulation of phosphorus in tooth enamel, . determination with radioactive phosphorus rate of formation of deoxyribonucleic acid (DNA) in malignant tumors of rats and authorize that entity in the therapy of X-rays,
. The use of radioactive isotopes for the first time in biochemistry and physiology allowed to understand the dynamics of chemical and physical reactions in living systems.
After Germanic occupation of Denmark in 1940. many scholars of this country have lost their jobs or were arrested. H., however, allowed to operate without interference until 1943. This summer, the Germans occupying troops occupied the territory of the institute, hoping to find there materials with scientific development of atomic weapons, although in reality such investigations are not conducted. By this time Bohr had already escaped to neutral Sweden, and X. quickly followed him. The Stockholm Institute for Research in the field of organic chemistry and biochemistry, among other works, he undertook a study on iron metabolism.
In 1943, Mr.. Nobel Prize in Chemistry is not awarded, but next year it was in 1943, Mr.. given X. 'for work on the use of isotopes as a tracer in the study of chemical processes'. Since the award ceremony during the war years had been breached, he received the award at the congress of the Royal Swedish Academy of Sciences. In his Nobel lecture, he summarized his extensive studies of living systems. 'The most significant result obtained in studies using tracer, - said H., - is, of course, the discovery of the dynamic state of the components of the organism. The molecules of which consist of plant and animal organisms, constantly regenerated '.
At the end of the war X. wished to remain in Sweden and in 1945. become a Swedish citizen. He continued to use the isotopic label in studies of different areas of physiology and biochemistry until 1961, when at the age of 76 years resigned.
X. married Pia Riis in 1924, they had a son and three daughters. A man of medium build, X. Throughout his active life, fond of foot and skiing. Over 30 years of scientific activities, he has published numerous articles in scientific journals. The last months of his life because of ill health, he held a medical clinic in Freiburg, where he died July 5, 1966, Mr.. a heart attack.
In addition to the Nobel Prize, X. was awarded Stanislao Cannizzaro of the Italian National Academy of Sciences (1929), . Copley Medal of Royal Society of London (1949), . Faraday Medal of the British Society of Chemistry (1950), . Medal of Niels Bohr Danish Engineering Society (1961) and others,
. He was awarded honorary degrees fourteen universities, including Cambridge, Uppsala, Freiburg, Ghent, Budapest. He was a member of many scientific societies and a foreign member of the Royal Society of London