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460
Democritus (Greece)
Democritus proposed that all matter is made up of particles which differ from each other in form, position and arrangement.
«http://scienceworld.wolfram.com/biography/Democritus.html» -
Isaac Newton (England)
Newtown proposed that all atoms were held together by attractions that we now call 'forces'.
«http://atomictimeline.net/index.php» -
John Dalton (England)
Dalton published the first table on atomic masses for some elements.
«http://www.buzzle.com/articles/john-daltons-atomic-theory.html» -
George Johnstone Stoney (Ireland)
Stoney proposed that electricity was made up of negative particles called electrons.
«http://atomictimeline.net/index.php» -
Joseph John Thomson (England)
Thomson discovered electrons and isotopes. He also whoed the existence of subatomic particles through cathode rays.
«http://www.chemheritage.org/discover/chemistry-in-history/themes/atomic-and-nuclear-structure/thomson.aspx» -
Max Planck (Germany)
He discovered the quantum theory which has revolutionised the understanding of atomic and sub-atomic processes.
«http://britannica/com/EBchecked/topic/462888/Max-Planck» -
Hantora Nagaoka (Japan)
Nagaoka demonstrated an atom using flat rings of electrons revolving around a poistively charged atom.
«http://atomictimeline.net/index.php» -
Robert Andrew Milikan (America)
Milikan allowed the ability to measure the charge to mass ratio of an electron.
«http://atomictimeline.net/index.php» -
Ernest Rutherford (Britain/New Zealand)
Rutherford established that the nucleus of an atom was very dense and also assumed that electrons were located outside of the nucleus.
«http://atomictimeline.net/index.php» -
Henry Gwy-Jeffreys Mosely (England)
Mosely determind the charges of the nuclei in an atom using x-ray tubes.
«http://atomictimeline.net/index.php» -
Niels Bohr (Denmark)
Bohr developed an explanation of atomic structure that underlies regularities of the periodic table. He aslo suggested that the outer shells of atoms could hold more than the inner shells and that the orbit determines the atom's chemical properties.
«http://www.lucidcafe.com/library/95oct/nbohr.html» -
James Chadwick (England)
Chadwick discovered the neutron using alpha particles.
«http://atomictimeline.net/index.php»
