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The nuclear reaction theorised by Meitner and Frisch and observed by Hahn and Strassmann. Nuclear fission was discovered in December 1938 by chemists Otto Hahn and Fritz Strassmann and physicists Lise Meitner and Otto Robert Frisch. Fission is a nuclear reaction or radioactive decay process in which the nucleus of an atom splits into two or ...
Nuclear fission is a reaction in which the nucleus of an atom splits into two or more smaller nuclei. The fission process often produces gamma photons, and releases a very large amount of energy even by the energetic standards of radioactive decay. Nuclear fission was discovered by chemists Otto Hahn and Fritz Strassmann and physicists Lise ...
History of atomic theory. The current theoretical model of the atom involves a dense nucleus surrounded by a probabilistic "cloud" of electrons. Atomic theory is the scientific theory that matter is composed of particles called atoms. The definition of the word "atom" has changed over the years in response to scientific discoveries.
When an atom is in an external magnetic field, spectral lines become split into three or more components; a phenomenon called the Zeeman effect. This is caused by the interaction of the magnetic field with the magnetic moment of the atom and its electrons.
Ernest Rutherford. Ernest Rutherford, 1st Baron Rutherford of Nelson, OM, FRS, HonFRSE [7] (30 August 1871 – 19 October 1937), was a New Zealand physicist who was a pioneering researcher in both atomic and nuclear physics. He has been described as "the father of nuclear physics", [8] and "the greatest experimentalist since Michael Faraday ". [9]
v. t. e. In nuclear physics, atomic physics, and nuclear chemistry, the nuclear shell model utilizes the Pauli exclusion principle to model the structure of atomic nuclei in terms of energy levels. [1] The first shell model was proposed by Dmitri Ivanenko (together with E. Gapon) in 1932. The model was developed in 1949 following independent ...
To explain the overall neutral charge of the atom, he proposed that the corpuscles were distributed in a uniform sea of positive charge. In this "plum pudding model", the electrons were seen as embedded in the positive charge like raisins in a plum pudding (although in Thomson's model they were not stationary, but orbiting rapidly). [32] [33]
3D animation of an atom incorporating the Rutherford model. The atomic nucleus shown expanded more than 10,000 times its size relative to the atom; electrons have no measurable diameter. The Rutherford model was devised by Ernest Rutherford to describe an atom. Rutherford directed the Geiger–Marsden experiment in 1909, which suggested, upon ...