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460
Democritus
Contributed the theory that everything is made up of atoms that move around constantly. -
Period: 460 to
History of Atomic Structure
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Isaac Newton
Proposed that all atoms were held together by attractions we now call ‘forces.’ -
John Dalton
One of the pioneers in founding modern atomic theory. -
G.J.Stoney
Introduced the term ‘electron’ as the fundamental unit quantity of electricity. -
J.J.Thompson
Discovered electrons and isotopes. -
Max Planck
Founded quantum theory, a theory describing the interactions of elementary particles or energy states. -
H. Nagaoka
Established our basic image of atom- rings of electrons orbiting a positively charged nucleus. -
E. Rutherford
He established that the nucleus was: very dense, very small and positively charged by probing alpha particles in a piece of thin gold foil. He also assumed that the electrons were located outside the nucleus. -
H.G.J.Moseley
Arranged the periodic table by atomic numbers and discovered that the atomic number of an element is equal to the number of protons in the nucleus. He also determined the charges on the nuclei of most atoms using x-ray tubes. -
Niels Bohr
Created a liquid drop model of the atomic nucleus. -
James Chadwick
Discovered the neutron.