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Democritus
Democritus came up wtih the idea that everying is made up of atoms, atoms are indestructible, and there is an infinite number of atoms. -
Isaac Newton
Isaac Newton began to understand that atoms or particles move and are not stationary. -
John Dalton
Proposed an "atomic theory" with spherical solid atoms based upon measurable properties of mass. -
Dmitri Mendeleev
Dmitri Mendeleev arranged elements into seven groups with similar properties. He discovered that the properties of elements "were periodic functions of their atomic weight". This became known as that Periodic Law. -
J. J. Thomson
J. J. Thomson discovered and identified the electron. -
Marie Curie
Marie Curie studied uranium and thorium and called their decay processs "radioactivity" -
R. A. Millikan
R. A. Millikan conducted an oil drop experiment which determined the charge (e=1.602 x 10 -19 coulomb) and the mass (m = 9.11 x 10 -28 gram) of an electron. -
Hans Geiger
Hans Geiger developed an electrical device to "click" when hit with alpha particles. -
Ernest Rutherford
Ernest Rutherford couldn't prove that atoms were positive or negative, but he theorized that atoms did have a charge and were located in a small nucleus. -
H. G. Moseley
H. G. Moseley determined the charges on the nuclei of most atoms. He defined the atomic number and his work was used to reorganize the periodic table based on atomic number instead of atomic mass. -
Niels Bohr
Niels Bohr developed an explanation of atomic structure that underlies regularities of the periodic table of elements. -
Heisenberg
Heisenberg described atomsby means of formula connected to the frequencies of spectral lines. He created the Proposed Principle of Indeterminancy, whcih states you cannot know both position and velocity of a particle. -
James Chadwick
James Chadwick was awarded the 1935 Nobel Prize in Physics for his discovery of the neutron in 1932. -
Lise Meitner
Lise Meitner conducted experiments verifying that heavy elements capture neutrons and form unstable products which undergo fission. The process ejects more neutrons continuing the fission chain reaction. -
Recent Discovery
Almost half a century after Peter Higgs predicted a Higgs boson as part of a mechanism (invented by a number of theorists) by which fundamental particles gain mass, the ATLAS and CMS experiments at the CERN lab discover the Higgs boson.
