Scientists

Akata Patel 4/5 10/5/08 Canova

Period Mr.

History of the Atom Extra Credit Within the past century, five additional scientists have made major contributions to the modern atomic model. These include Louis de Broglie, Werner Heisenberg, Paul Dirac, Hideki Yukawa, and Enrico Fermi. Louis de Broglie was a member of the French Academy, Permanent Secretary of the Academy of Sciences, and Professor at the Faculty of Sciences at Paris University. De Broglie was form Paris, Farnce.In 1924, Louis de Broglie proposed that all moving particles–particularly subatomic particles such as electrons–exhibit a degree of wave-like behavior. In 1927, de Broglie made it so that you can predict the wave properties of matter theoretically. He came up with the Quantum Theory. Louis de Broglie believed that any moving particle or object had an associated wave. De Broglie thus created a new field in physics, wave mechanics, uniting the physics of light and matter. For this he won the Nobel Prize in Physics in 1929. Quantum mechanics is the foundation of chemistry, because it deals with subatomic particles, as well as atoms, molecules, elements, compounds, and much larger systems.This theory gives good interpretations of the phenomena of the atomic and subatomic world. The study of quantum mechanics lead us to understand the material and the universe beyond the general perception of matter by our ordinary senses of tasting, seeing, hearing, feeling, and sensing.The discovery of The Quantum Theory was considered important towards atomic theory because it helped in describing atomic structures. Niels Bohr developed an explanation of atomic structure that underlies regularities of the periodic table of elements. His atomic model had atoms built up of sucessive orbital shells of electrons. DE Broglie Improved this atomic model theory by dicovering that electrons had a dual nature-similar to both particles and waves(Particle/wave duality). The quantum theory does much more than explaining the structure of the simplest atom, it rationalizes the existence of the chemical elements. The most widely used periodic table of chemical elements today is based on the results of quantum theory. What we tend not to appreciate today is the hard work and ingenuity that went into the development of the quantum theory we today take for granted. Werner Heisenberg was a German theoretical physicist, best known for enunciating the uncertainty principle of quantum theory.Heisenberg was from Germany. He made important contributions to quantum mechanics, nuclear physics, quantum field theory, and particle physics. Heisenberg was also part of the German nuclear energy project.In 1925, Max Born and Heisenberg formulated the matrix mechanics representation of quantum mechanics. He described atoms by means of formula connected to the frequencies of spectral lines. Heisenberg also proposed the Principle of Indeterminancy - you can not know both the position and velocity of a particle. He came up with the theory of Quantum Mechanics. For this theory and the applications of it which resulted especially in the discovery of allotropic forms of hydrogen, Heisenberg was awarded the Nobel Prize for Physics for 1932. His discovery changed the atomic model theory because it showed that you cannot always assign to an electron a position in space at a given time, nor follow it in its orbit, so that you cannot assume that the planetary orbits postulated by Niels Bohr actually exist. Heisenburg's theory was

considered important because it cleared up misunderstandings about the previous theories. Paul Dirac was a British theoretical physicist. Dirac was from Britain. Dirac made fundamental contributions to the early development of both quantum mechanics and quantum electrodynamics. Among other discoveries, he formulated the Dirac equation, which describes the behavior of fermions and which led to the prediction of the existence of antimatter. Dirac shared the Nobel Prize in physics for 1933 with Erwin Schrödinger, for the discovery of new productive forms of atomic theory.In 1933, Dirac showed that the existence of a single magnetic monopole in the universe would suffice to explain the observed quantization of electrical charge. Paul Dirac's discovery was important towards the atomic theory because he expanded on it and explained the atomic theory better. Pauls Dirac's discovery changed the atomic mdel theory because it had new productive forms of atomic theory. Hideki Yukawa was from Tokyo, Japan. He was a japanese scientist who won the Nobel Prize for physics in 1949. Yukawa is known for his theory of how the nuclear force holds the nucleus together. This theory was imortant because it helped for him to predict the existence of the meson, a subatomic particle(1935). His discovery changed the atomic model theory because it added the idea of the composite paticles called mesons to an atom. Enrico Fermi was an Italian physicist most noted for his work on the development of the first nuclear reactor, and for his contributions to the development of quantum theory, nuclear and particle physics, and statistical mechanics. Fermi was awarded the Nobel Prize in Physics in 1938 for his work on induced radioactivity. Fermi conducted the first controlled chain reaction releasing energy from the atoms nucleus(nuclear reactor). Enrico Fermi's discovery was important towards the atomic theory beacause he discovered the nuclear reactor. The nuclear reactor also changed the atomic model theory by adding the fact that energy is released fromt he atom's nucleus.