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Period: to
Reserach of the atomic theory
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John Dalton
"All matter is made of atoms." He also rediscovered George Hadley's theory of atmospheric circulation. In 1787 at age 21 he began to keep a meteorological diary in which, during the succeeding 57 years, he entered more than 200,000 observations. -
Antoine Lavoisier
Characteristic of Lavoisier’s chemistry was his systematic determination of the weights of reagents and products involved in chemical reactions, including the gaseous components, and his underlying belief that matter identified by weigh would be conserved through any reaction.To propagate his ideas, in 1789 he published a textbook, Traité Élémentaire de chimie -
Joseph Louis Proust
His law states that a compound is composed of exact proportions of elements by mass regardless of how the compound was created. -
Michael Faraday
In 1821 he published his work on electromagnetic rotation (the principle behind the electric motor). He was able to carry out little further research in the 1820s, busy as he was with other projects -
Max Planck
the problems of radiation processes engaged his attention and he showed that these were to be considered as electromagnetic in nature. From these studies he was led to the problem of the distribution of energy in the spectrum of full radiation. -
J.J. Thomas
He found out that the size of the an electron is so small that its mss is an insignificant fraction of the mass of an atom of hydrogen. -
Ernest Rutherford
He worked jointly with Thomson on the behaviour of the ions observed in gases which had been treated with X-rays. -
Henri Becquerel
By accident, he discovered that the uranium salts spontaneously emitted a penetrating radiation that could be registered on a photographic plate. -
Marie Curie
They announced the discovery of two new elements, radium and polonium and earned a Nobel Prize. Curie served as the director of the Red Cross Radiology Service. -
Albert Einstein
Einstein confronted the apparent contradiction between two principal theories of physics: Isaac Newton’s concepts of absolute space and time and James Clerk Maxwell’s idea that the speed of light was a constant. He introduced his special theory of relativity, which held that the laws of physics are the same even for objects moving in different inertial frames, and that the speed of light is a constant in all inertial frames -
Robert Milikan
Between 1908-1917 Robert Milikan measured the charge of an electron. He was able to show that the charge of a drop was always an integral multiple of a small, but finite value. Confirmimng Thomas' hypothesis. -
Niels Bohr
Niels Bohr proposed a theory for the hydrogen atom based on quantum theory that energy is transferred only in certain well defined quantities. Electrons should move around the nucleus but only in prescribed orbits. -
Ernest Schrodinger
He combined the equations for the behavior of waves with the de Broglie equation to generate a mathematical model for the distribution of electrons in an atom. This consists of mathematical equations known as wave functions -
Louis DeBroglie
they served as the basis for developing the general theory nowadays known by the name of wave mechanics, a theory which has utterly transformed our knowledge of physical phenomena on the atomic scale. -
James Chadwick
Discovered the nuetron. He could show that in the reaction, a neutral particle with a mass about that of a proton, was emitted. Ernest Rutherford had earlier proposed that such a neutral particle might exist in nuclei. The particle was discovered and was named neutron. -
Lise Meitner
Meitner was part of the Hahn-Meitner-Strassmann team that worked on "transuranium-elements" from 1935 onward, which led to the radiochemical discovery of the nuclear fission of uranium and thorium in December 1938 -
Otto Hahn
While working jointly with Dr. Strassmann, Hahn discovered the fission of uranium and thorium in medium heavy atomic nuclei and his first work on these subjects appeared on 6th January and 10th February, 1939, in Naturwissenschaften. -
Glen T. Seaborg
His work in this area also led to his development of the actinide concept and the arrangement of the actinide series in the periodic table of the elements.
