Parts of an atom diagram

Atomic Timeline

  • Plato
    440 BCE

    Plato

    He said atoms must come from triangles, squares, pentagons, etc.
  • Democritus
    400 BCE

    Democritus

    He said matter could be divided into smaller and smaller pieces until the smallest piece was discovered.
  • Robert Boyle

    Robert Boyle

    He stated that all things are made of atoms and he also created Boyles Law.
  • Antone Lavoisier

    Antone Lavoisier

    He said that the total mass of products and reactants in a chemical reaction is always the same.
  • The Alchemists

    The Alchemists

    The Alchemists layed down the foundation for the Periodic Table.
  • John Dalton

    John Dalton

    He said that compounds were atoms from different elements combined together. He also proposed the atomic theory
  • Amadeo Avagadro

    Amadeo Avagadro

    He said that equal volumes of gas contain equal numbers of molecules and that elementary gases such as hydrogen, nitrogen, and oxygen were composed of atoms.
  • Dmitri Mendeleev

    Dmitri Mendeleev

    He discovered of the periodic law and the first periodic table.
  • Henry G. J. Mosely

    Henry G. J. Mosely

    He stated that each element contains a unique number of protons; their atomic number.
  • JJ Thompson

    JJ Thompson

    He provided the first hint that an atom is made of even smaller particles.
  • Pierre and Marie Curie

    Pierre and Marie Curie

    They discovered 2 elements: polonium and radium.
  • Albert Einstein

    Albert Einstein

    He mathematically proved the existence of atoms.
  • Ernest Rutherford

    Ernest Rutherford

    He stated that atoms are filled with a positively charged material. He theorized that atoms have a small dense positively charged center called nucleus.
  • Robert Millikan

    Robert Millikan

    He measured the change of an electron using oil droplets.
  • Neils Bohr

    Neils Bohr

    He stated that the mass of the atom is contained mostly in the nucleus. And that electrons move in orbit around the nucleus.
  • Erwin Schrodinger

    Erwin Schrodinger

    He formulated a wave equation that calculated the energy levels of electrons in atoms.
  • Heisenberg

    Heisenberg

    A particles position and momentum cannot be known exactly
  • James Chadwich

    James Chadwich

    He discovered neutrons.