Niels Born

Niels Henrick David Bohr (Copenhaga, 7 of October of 1885 - Copenhaga, 18 of November of 1962) was a Danish physicist whose works had contributed decisively for the understanding of the atomic structure and the quantum physics. Its father, Christian Bohr, were physiology professor, and its mother, Ellen (name of Adler bachelor), came from a Jewish family. One took leave in its native city in 1911 and worked with Joseph John Thomson and Ernest Rutherford in England. In 1913, applying the theory of the quantification to the elétrons/electrões of the atomic model of Rutherford, she obtained to interpret some of the properties of the spectral series of hydrogen and the structure of the periodic system of the elements. She formulated the principle of the correspondence and, in 1928, of the complementaridade. She still studied the nuclear model of the liquid drop, and before the discovery of the plutónio, she foresaw the property of the split, analogous to the one of the U-235. Bohr received the Prémio Nobel de Física in 1922. Its theory for the explanation of the atomic model considered by Rutherford in 1911, taking in account the quantum theory (formulated for Max Planck in 1900), was not taken the serious one. Later, in elapsing of the decade and the decade of 1920, some physicists had helped to create the existing model today. Between these physicists we can cite Einstein, Of Broglie, Schrödinger, Heisenberg, Of Pauli, among others. [ to edit ] Life and workmanship When still she was student, an announcement, of the Academy of Sciences of Copenhaga, a prize for who decided one definitive scientific problem took it to carry through it a theoretical and experimental inquiry on the tension of the surface provoked for the spurt oscillation fluid. This work, taken the handle in the laboratory of its father, gained the prize (the gold medal) and was published in "Transactions of the Royal Society", in 1908. Bohr continued its inquiries and its thesis of doutoramento happened on the properties of metals with the aid of the theory of electrons that still today it is a classic in the field of the physics. In this Bohr research it was collated with the implications of the quantum theory of Planck. In the Autumn of 1911, Bohr was changed for Cambridge, where it worked in the Cavendish Laboratory under the orientation of J. J. Thomson. In the Spring of 1912, Niels Bohr started to work in the Laboratory of Rutherford Professor, in Manchester. In this laboratory, Bohr carried through a work on the absorption of rays alpha, that it was published in the "Philosophical Magazine", in 1913. However, Bohr started to dedicate to it the study of the structure of the atom, being based on the discovery of the atomic nucleus, carried through for Rutherford.
In the same year, Bohr married Margrethe Norlund, who would come to have six children. When it returned to the Denmark in 1913, Bohr looked for to extend to the atomic model considered by Rutherford the quantum concepts of Planck. Bohr believed that, using the quantum theory of Planck, it would be possible to create a new atomic model, capable to explain the form as eletróns absorbs and emits radiating energy. These phenomena were particularly visible in the analysis of the luminous specters produced by the different elements. In contrast of the produced one for the solar light, these specters present lines of light with specific, separate localizations for dark areas. No theory obtains until then explaining the cause of this distribution. In 1913, Bohr, studying the hydrogen atom, obtained to formulate a new model atomic. Bohr concluded that eletrón of the atom did not only emit radiations while it remained in the same orbit, emitting them when more distant orbit of the nucleus is dislocated from a level of bigger energy (, where its - of the electron - kinetic energy tends to diminish while that its potential energy tends to increase; but, its total energy increases) for another one of lesser energy (less distant orbit, where its energy kinematics tends to increase and its potential energy tends to diminish; but, its total energy diminishes). The quantum theory allowed it to formulate this conception in more necessary way: the orbits would not be situated to any distances of the nucleus, for the the opposite, only some orbits would be possible, each one of them corresponding to a clear-cut level of energy of eletrón. The transistion of an orbit for the other would be made by jumps therefore, when absorbing energy, eletrón would jump for a externa(conceito orbit quantum) e, to the emitiz it, would pass to the other most internal one (concept photon). Each one of these emissions appears in the specter as a well located luminous line. theory of Bohr, that successively was enriched, represented a decisive step in the knowledge of the atom. Thus, the theory of Bohr allowed the elaboration of the quantum mechanics leaving of a solid experimental base. The publication of the theory on the constitution of the atom had an enormous repercussion in the scientific world. With only 28 years of age, Bohr was a famous physicist with one shining career. Of 1914 the 1916 were professor of Theoretical Physics in the University of Victoria, in Manchester. Later, it came back toward Copenhaga, where director of the Institute of Theoretical Physics in 1920 was nominated. In 1922, its contribution was internationally recognized when it received the Prémio Nobel from the Physics. In the same year, Bohr wrote the book "The Theory of Spectra and Atomic Constitution", whose second edition was published in 1924. With the objective to compare the results gotten by means of the quantum mechanics with the results that, with the same system, if they would get in the classic mechanics, Bohr enunciated the principle of the correspondence. According to this principle, the classic mechanics represents the limit of the quantum mechanics when this deals with phenomena of the macrocospic world. Bohr still studied the interpretation of the structure of complex atoms, the nature of radiations X and the gradual variations of the chemical properties of the elements. Bohr was also dedicated to the study of the atomic nucleus. The model of nucleus in form of "water drop" showed favorable very for the interpretation of the fenómeno of the fissão of the Uranian one, that it opened way for the use of the nuclear energy. Bohr discovered that during the fissão of an atom of Uranian an enormous amount of energy was gotten loose and repaired then that it was about a new energy source of highest potentialities. Bohr, with the purpose to use to advantage this energy, was until Princeton, in the Philadelphia, where if it found with Einstein and Fermi to argue with these the problem In 1933, together with its Wheeler pupil, Bohr deepened the theory of the fissão, evidencing the basic paper of Uranian the 235. These studies had allowed shortly afterwards to foresee also the existence of a new element, discovered: the plutónio. In 1934, and published the book "Atomic Theory the Description of Nature", that it was reedited in 1961. In January of 1937, Bohr participated in the Fifth Conference of Theoretical Physics, in Washington, in which it defended the interpretation of L. Meitner and Otto R. Frisch, also of the Institute of Copenhaga, for the fissão of the Uranian one. According to this interpretation, an atomic nucleus of unstable mass was as a water drop that if breaches. Three weeks later, the beddings of the theory of the "water drop" had been published in the magazine "Physical Review". To this publication many had been followed others, all related with the atomic nucleus and the disposal and characteristics of the electrões that turn in lathe of it. One year after if having refugee in England, due to Nazi occupation of the Denmark, Bohr it was changed for the United States, where it occupied the position of consultant of the laboratory of atomic energy of Los Alamos. In this laboratory, some scientists initiated the construction of the atomic bomb Bohr, understanding the gravity of the situation and the danger that this bomb could represent for the humanity, directed it Churchill and Roosevelt, in one appeals to its responsibility of heads of State, trying to prevent the construction of the atomic bomb. But the attempt of Bohr was em.vão. In July of 1945 the first experimental atomic bomb blew up in Alamogordo. In August of this exactly year, an atomic bomb destroyed the city of Hiroshima. Three days later, one second bomb was launched in Nagasáqui. In 1945, finda the World War II, Bohr returned to the Denmark, where she was elect president of the Academy of Sciences. Bohr continued to support the advantages of the scientific contribution between the nations and for this he was promotional of organized scientific congresses periodically in the Europe and the United States. In 1950, Bohr wrote the "Open Letter" to the Nations Joined in defense of the preservation of the peace, for considered it as indispensable condition for the thought freedom and from research In 1957, Niels Bohr received the Prémio Atoms for the Peace At the same time, the Institute of Theoretical Physics, for directed it since 1920, was affirmed as one of the main intellectual centers of the Europe. Bohr died the 18 of November of 1962, one victim trombose, to the 77 years of age.

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