Atomic Theory Timeline

  • Period: 322 to


    (note the timespan above represents Aristotle's lifespan and is 384-322 BC) Aristotle contradicted Deomocritus' beleifs about atoms and reasoned that things cannot be made of small indivisible particles.
  • 323

    Alexander the Great 2

    Alexander the Great died after a lifetime of success in conquering the known world. (note: 323 BC)
  • 356

    Alexander the Great

    In 356 (BC), Alexander the Great was born.
  • Period: 370 to 460


    (note: the dates above represent the lifespan of Democritus and are 460-370 BC) Democritus reasoned that all things were made of miniscule, but indestuctible atoms (atomos). He also believed there were different types of atoms and they have mass.
  • Joseph Proust

    Joseph Proust
    Joseph Proust stated that all compounds conatin elements of a fixed proportion, also known as his law of definite proportions.
  • John Dalton

    John Dalton
    Dalton supported Democritus' veiws about atoms and created a four point atomic theory to support/express his opinion on the subject. Unlike Democritus, he utilized the scientific method in order to obtain his theory.
  • Henry Becquerel

    Henry Becquerel
    Becquerel discovered the property of radioactivity that some substances have while experimenting with Uranium.
  • J.J Thompson

    J.J Thompson
    Discovered that electrons have a negative electron charge and created the plum pudding electron model where the electrons (plums) exist in a positive environment (the pudding). This theory is also known as the raisin bread theory.
  • Max Planx

    Max Planx
    Planx discovered heat radiation (also known as Plank's law of black body radiation) which became the basis for the quantum theory.
  • Noble Prize

    The first ever noble prize was awarded.
  • Teddy Bear

    The popular teddy bear was introduced.
  • The Great Train Robery

    First silent movie created and calledTHE GREAT TRAIN ROBBERY.
  • Subway

    New York subway was first opened.
  • Earnest Rutheford

    Earnest Rutheford
    Discovered the nucleus of atoms while sending a beam of alpha particles through a thin foil of gold and noticing that some beams rebounded of of the nuclei. This lead to the Rutheford Electrom Model.
  • Oreos

    The now famous Oreo Cookie was first introduced.
  • Niels Bohr

    Niels Bohr
    Created an electron model where electrons orbit the nucleus in a way where they don't loose energy. This is known as the beginning of quantum mechanics.
  • Robert Millikan

    Robert Millikan
    Millikan calculated the mass of an electron (approximatley 1/1840 the mass of a hyrdogen atom).
  • Olympics

    First Winter Olympic took place.
  • Louis Victor de Brogile

    Louis Victor de Brogile
    Using evidence he conjectured that electrons move in a wave like fashion.
  • Erwin Schrodinger

    Erwin Schrodinger
    Schrodinger developed a mathematical equation that describes the motion of electrons in atoms - which led to the theory of the electron cloud.
  • Werner Heisenberg

    Werner Heisenberg
    Created the Heisenberg uncertainty princple by stating that it is impossible to know exactly both the velocity and position of a (microscopic) particle at one time.
  • Uh-Oh!

    U.S stock market crashed, sparking the Great Depression.
  • James Chadwick

    James Chadwick
    Discovered that nuetrons existed in the nucleus with the protons and have a mass similar to protons.
  • WW2

    WW2 began.