Atomic Timeline

  • 500 BCE

    The Alchemists (500 BCE)

    The Alchemists (500 BCE)
    The Alchemists contributed to the atom by breaking down the chemical compositions of fire, wind, earth, and water which eventually evolved into the Periodic Table of Elements. (500 BCE)
  • 427 BCE

    Plato (427 BCE)

    Plato (427 BCE)
    Plato contributed to the atom when he was convinced that atoms of matter must derive from 5 fundamental solids. (427 BCE)
  • 400 BCE

    Democritus (400 BCE)

    Democritus (400 BCE)
    Democritus contributed to the atom when he theorized that all material bodies were made up of indivisibly small "atoms". (400 BCE)
  • Robert Boyle (1661)

    Robert Boyle (1661)
    Robert Boyle contributed to the atom when he helped develop the definition of an element. (1661)
  • Antone Lavoisier (1772)

    Antone Lavoisier (1772)
    Antone Lavoisier contributed to the atom when he discovered that the total mass of products and reactants in a chemical reaction is always the same (conservation of mass) which meant that the same number and kind of atom is present before and after a chemical change. (1772)
  • Billiard Ball Model (1803)

    Billiard Ball Model (1803)
    The Billiard Ball Model was created in 1803 by John Dalton
  • John Dalton (1808)

    John Dalton (1808)
    John Dalton contributed to the atom when his atomic theory was the first complete attempt to describe all matter in terms of atoms and their properties. (1808)
  • Amedeo Avogadro (1811)

    Amedeo Avogadro (1811)
    Amedeo Avogadro contributed to the atom when he discovered that hydrogen, nitrogen, and oxygen were composed of 2 atoms. (1811)
  • Dmitri Mendeleev (1869)

    Dmitri Mendeleev (1869)
    Dimitri Mendeleev contributed to the atom when he devised the periodic classification of the chemical elements, in which the elements are arranged in order of increasing atomic weight. (1869)
  • Plum Pudding Model (1897)

    Plum Pudding Model (1897)
    The Plum Pudding Model was created in 1897 by JJ Thompson
  • JJ Thompson (1897)

    JJ Thompson (1897)
    JJ Thompson contributed to the atom when he proved that all atoms contained tiny negatively charged subatomic particles or electrons.(1897)
  • Pierre and Marie Curie (1898)

    Pierre and Marie Curie (1898)
    Pierre and Marie Curie contributed to the atom when they discovered ionizing, which was penetrating rays created by certain atoms. (1898)
  • Albert Einstein (1905)

    Albert Einstein (1905)
    Albert Einstein contributed to the atom when he mathematically proved the existence of atoms which revolutionized all the sciences. (1905)
  • Robert Millikan (1910)

    Robert Millikan (1910)
    Robert Millikan contributed to the atom when he determined the magnitude of the electron's charge. (1910)
  • Ernest Rutherford (1911)

    Ernest Rutherford (1911)
    Ernest Rutherford contributed to the atom by discovering that the atom consisted of mostly empty space, with its mass concentrated in a central positive nucleus. (1911)
  • Solar System Model (1913)

    Solar System Model (1913)
    The Solar System Model was created in 1913 by Ernest Rutherford
  • Neils Bohr (1913)

    Neils Bohr (1913)
    Neils Bohr contributed to the atom when he proposed a theory for the hydrogen atom and realized that electrons did not crash into the nucleus. (1913)
  • Henry G. J. Mosely (1913)

    Henry G. J. Mosely (1913)
    Henry G. J. Mosely contributed to the atom when he proved that every element's identity is uniquely determined by the number of protons it has. (1913)
  • Electron Cloud Model (1926)

    Electron Cloud Model (1926)
    The Electron Cloud Model was created in 1926 by Erwin Schrodinger
  • Erwin Schrodinger (1926)

    Erwin Schrodinger (1926)
    Erwin Schrodinger contributed to the atom when he described the likelihood of finding an electron in a certain position. (1926)
  • Werner Hisenberg (1927)

    Werner Hisenberg (1927)
    Werner Hisenberg contributed to the atom when he discovered that a particles position and momentum could not be known exactly. (1927)
  • James Chadwick (1932)

    James Chadwick (1932)
    James Chadwick contributed to the atom when he discovered neutrons in atoms. (1932)