Chemistry Timeline

By gwalters23
  • Period: 500 BCE to

    Alchemists

    The alchemists discovered acids and experimented with turning base metals into gold.
  • 450 BCE

    Aristotle

    Aristotle creates the Theory of Empedocles which states that all matter is composed of 4 elements, earth, fire, air, and water.
  • 442 BCE

    Democritus

    Democritus puts forward the concept of atoms. He claims that the smallest pieces of matter are atoms and they make up all things.
  • 1492

    Columbus Arrives in America

  • Robert Boyle

    Robert Boyle put forward the theory that all matter was composed of particles with differing shapes and motion. He is called the father of modern science for being the first to document his experiments.
  • Period: to

    American Revolution

  • Period: to

    American Civil War

  • Dmitri Mendeleev

    Dmitri Mendeleev created one of the first periodic tables. He arranged the elements by increasing atomic mass to present groups with different properties. What made his periodic table stand out from others was how he left empty spaces for elements yet to be discovered, predicting multiple elements that were later added to the periodic table.

  • J.J. Thomson

    J.J. Thomson discovered the electron through experiments involving electric beams within cathode ray tubes. He created the "Plum Pudding Model" of the atom which displayed all the atomic particles mixed together, with electrons with negative charges surrounded by positive charges to create a neutral charge.

  • Ernest Rutherford

    Ernest Rutherford discovered the structure of the nucleus of an atom by studying the deflection of alpha particles shot through gold foil. He put forward the model that the nucleus contains all of the atom's positive charge as well as its entire mass.

  • Robert Millikan

    Robert Millikan discovered the charge of the electron though experiments where he measured the movement of electrically charged oil drops to find their charge and the charge of its electrons.

  • Hans Geiger

    Hans Geiger was involved in Ernest Rutherford's experiments that led to his model of the atom. Geiger also created the Geiger Counter which measured ionizing radiation.

  • Neils Bohr

    Neils Bohr created the Bohr model, which shows a positively charged nucleus surrounded by orbiting electrons. The number of electrons in the outermost orbit would determine properties of the element.
  • Period: to

    World War 1

  • James Chadwick

    James Chadwick proved the existence of neutrons, atomic particles with no charge.
  • Period: to

    World War 2

  • Hiroshima