1_Democritus

1_Democritus

1. John Dalton

   • John Dalton used weight to differentiate types of atoms, finding elements and compounds. He also discovered that atoms are spherical. That begins the basis for atomic models, and elements.
   • JJ Thomson
     • JJ Thomson used rays to discover electrons, a particle that makes up atoms. His finding showed us that atoms are more complex.
     • Max Planck
       • Planck discovered the quantum theory, a theory centered around light. His discovery helped Einstein discover e=mc2, an equation that relates to electron masses, and light production.
       • Robert Millikan
         • Robert Millikan was able to measure the electron's charge.  He was able to find that they have a negative charge.
         • Ernest Rutherford
           • Rutherford proved the existence of the nucleus, and created a theory on the structure of the atom. His discovery helped to know the type of element, as they are determined by protons in the nucleus.
           • Neils Bohr
             • Niels Bohr created the Bohr model, a model showing the electron shells and nucleus. His discovery of where electrons are found is still used today.
             • Erwin Schrodinger
               • Schrodinger developed an equation to show how electrons move with time, and proved that electrons move in a wave form.  That gave us more precise look at where electrons are, and their energy.
               • 1926
             • 1913
           • 1909
         • 1908
       • 1900
     • 1898
   • 1803

2. Atomic Theory Timeline

   • James Chadwick
     • Chadwick discovered neutrons, the other particle in the nucleus. His discovery completed the atomic components, and helped us understand atomic weight, and isotopes.
     • 1931
   • Modern Electron Cloud Model
   • Rebecca Bradley

3. 442Bc

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