Old Dudes Time Line Project

Contributions to the Field of Chemistry

Period: 350 to Dec 31, 2012

Democritus - 460 B.C

460

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Developed the idea of atoms in a void.

Medieval Alchemy

Feb 28, 1600

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Developed the idea of "Corpuscles" that were subject to attractive and repulsive forces.

John Dalton

Feb 28, 1766

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Proposed a modern atomic model based on experimentation not on pure reason.

Henri Becquerel

Mar 1, 1852

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Discovered that X-rays excite fluorescence in certain substances

Neils Bohr

Mar 1, 1855

Link-Formulated the ‘complementarity principle’
-Made major contributions to the work on radioactivity that led to the discovery and exploitation of nuclear fission
-created the liquid-drop model of the nucleus

J.J Thompson

Feb 28, 1856

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Discovered Electrons and created the Raisin Pudding Model

Marie and Pierre Curie (1867 & 1856)

Mar 1, 1867

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They established that the heavy element thorium was radioactive and discovered two new elements: polonium and radium. They refined techniques for extracting radium from ores.

Ernest Rutherford

Mar 1, 1871

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Shot alpha (α) particles at gold foil and discovered that a “nucleus” is positive & holds most of an atom’s mass.

James Chadwick

Mar 1, 1932

LinkProved that neutrons, neutral particles in the nucleus that made up approximately half the mass of an atom, did exist