1_Democritus

Annotations:

• Democritus discovered the existence of tiny particles, and that matter is composed of indivisible pieces. His discovery began the scientific discovery of atoms.

1. John Dalton

   Annotations:

   • 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.
   1. JJ Thomson

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      • JJ Thomson used rays to discover electrons, a particle that makes up atoms. His finding showed us that atoms are more complex.
      1. Max Planck

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         • 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.
         1. Robert Millikan

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            • Robert Millikan was able to measure the electron's charge.  He was able to find that they have a negative charge.
            1. Ernest Rutherford

               Annotations:

               • 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.
               1. Neils Bohr

                  Annotations:

                  • 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.
                  1. Erwin Schrodinger

                     Annotations:

                     • 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.
                     2. 1926
                  2. 1913
               2. 1909
            2. 1908
         2. 1900
      2. 1898
   2. 1803
2. Atomic Theory Timeline
   1. James Chadwick

      Annotations:

      • Chadwick discovered neutrons, the other particle in the nucleus. His discovery completed the atomic components, and helped us understand atomic weight, and isotopes.
      1. 1931
   2. Modern Electron Cloud Model
   3. Rebecca Bradley
3. 442Bc