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Joseph Proust
Joseph Proust was born on September 26, 1754 and died on July 5, 1826. He published the law of definite proportions. This law states that a compound is composed of exact proportions of elements by mass regardless of how the compound was created.
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John Dalton's Atomic Theory
John Dalton was born on September 6, 1766 and he died on July 27, 1844. He came up with several theories which consist of, all matter is made up of atoms, atoms are indivisible and indestructible, all atoms of a given element are identical in mass and properties, compounds are formed by a combination of 2 or more different kinds of elements, a chemical reaction is a rearrangement of atoms.
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Amedeo Avogado's Atomic Theory
Amedeo Avogado was born on august 9, 1776 and he died on July 9, 1856. Hypothesized that equal volumes of gases at the same temperature and pressure contain equal numbers of molecules. He also hypothesized that simple gases were not formed of solitary atoms but were instead compound molecules of two or more atoms. He referred to atoms as elementary molecules.
PICTURE: http://www.ep.ph.bham.ac.uk/DiscoveringParticles/blocks/atom/images/atom.png -
Dmitri Mendeleev
He organized, created, and published the first periodic table of elements. The call him the "Father of the periodic table".
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JJ Thomson's Atomic Theory
JJ Thomson was born on December 18, 1856 and died on August 30, 1940. JJ discovered the electron when attempting a cathode ray experiment. Made his model of an atom as a sphere of positive matter in which electrons are positioned by electrostatic forces. His techniques led to the development of the mass spectrograph.
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Marie Curie's Atomic Theory
Marie Curie was born on November 7, 1867 and she died on July 4, 1934. She discovered that radioactivity showed that the atom was divisible which disproves John Dalton’s atomic theory. She postulated the existence of powerful radioactive element in pitch ores. She proved you can exactly measure the strength of radiation from uranium. The ability to emit radiation does not depend on the arrangement of the atoms in a molecule it must be linked to the interior of the atom itself.
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Ernest Rutherford's Atomic Theory
Ernest Rutherford was born on August 30, 1871 and he died on October 19, 1937. He discovered alpha and beta rays. Set forth laws of radioactive decay. He identified alpha particles as the nucleus of helium. Postulated the nuclear structure of the atom. His experiments showed that when alpha particles are fired into gas atoms, a few are violently deflected, this implies a dense, positively changed central region containing most of the atomic mass.
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Hans Geiger's Atomic Theory
Hans Geiger was born on September 30, 1882 and he died on September 24, 1945. He invented the Geiger counter which was a detector of radioactivity. The Geiger counter counted the number of alpha particles and other iodizing radiation. He helped to discover alpha particles are the nucleus of helium. He discovered that alpha particles had 2 units of charge, also he found out alpha particles are deflected through large angles when they strike a thin leaf of gold or silver. His Geiger-
Nutall rule -
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Niels Bohr's Atomic Theory
Niels Bohr was born on October 7, 1885 and he died on November 18, 1962. He postulated based on quantum theory that electrons travel around an atomic nucleus in a stationary orbit. His work also led to the theory of different energy levels in atoms, that is if an electron drops from a higher to a lower orbit, it must release or absorb energy.
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Enrico Fermi (cont.)
Enrico discovered the Statistical laws -
Enrico Fermi (cont.)
Fermi Evolved the B-decay theory -
Enrico Fermi's Atomic Theory
Enrico Fermi was born on September 29, 1901 and he died on November 28, 1954. He developed the first nuclear reactor. Discovered the splitting of the atom , or nuclear fission. Completed the first successful chain reaction when he was working on the manhattan project. Devloped a theory that states a universal magnetic field- acting as a giant accelerator.
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