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Scientists that Contributed to the Atomic Theory

Timeline created by 13dvandorick in Science and Technology
Event Date: Event Title: Event Description:
J991825 small square Isaac Newton Proposed a mechanical universe with small solid masses in motion.
John dalton reich chemmistry small square John Dalton Proposed an "atomic theory" with spherical solid atoms based upon measurable properties of mass.
Michael faraday small square Michael Faraday Studied the effect of electricity on solutions, coined term "electrolysis" as a splitting of molecules with electricity, developed laws of electrolysis. Faraday himself was not a proponent of atomism
Plucker small square J. Plucker Built one of the first gas discharge tubes ("cathode ray tube").
Dmitri mendeleev small square Dmitri Mendeleeff Arranged elements into 7 groups with similar properties. He discovered that the properties of elements "were periodic functions of the their atomic weights". This became known as the Periodic Law.
Pe 62 small square G.J. Stoney Proposed that electricity was made of discrete negative particles he called "electrons". (Link to info on electrons)
Jj thomson small square J.J. Thomson Used a CRT to experimentally determine the charge to mass ratio (e/m) of an electron =1.759 x 108 coulombs/gram.
1911 gfoil 02 small square Rutherford Studied radiations emitted from uranium and thorium and named them alpha and beta. And using alpha particles as atomic bullets, probed the atoms in a piece of thin (0.00006 cm) gold foil. He established that the nucleus was: very dense,very small and positively charged. He also assumed that the electrons were located outside the nucleus.
Soddy small square Soddy Observed spontaneous disintegration of radioactive elements into variants he called "isotopes" or totally new elements, discovered "half-life", made initial calculations on energy released during decay.
Chfa 03 img0588 small square H.G.J. Moseley Using x-ray tubes, determined the charges on the nuclei of most atoms. He wrote"The atomic number of an element is equal to the number of protons in the nucleus". This work was used to reorganize the periodic table based upon atomic number instead of atomic mass.
Francis william aston small square Francis William Aston Discovered the existence of isotopes through the use of a mass spectrograph.
Niels bohr small square 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.
17306 de broglie lg small square de Broglie Discovered that electrons had a dual nature-similar to both particles and waves. Particle/wave duality. Supported Einstein.
Chadwick small square James Chadwick Using alpha particles discovered a neutral atomic particle with a mass close to a proton. Thus was discovered the neutron.
Fermi 2 small square Enrico Fermi CitationsConducted the first controlled chain reaction releasing energy from the atoms nucleus.
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