Atomic Model/Theory Timeline

  • Sep 27, 1540

    Empedocles 450 B.C.

    Empedocles 450 B.C.
    Empedocles beleived that all matter is composed of elements, Fire, air, water and earth.
  • Sep 27, 1560

    Plato 405 B.C.

    Plato 405 B.C.
    Plato developed the foundations of metaphysics and epistemology by studying the doctrines of cratylus and the work of pythagoras and parmenides.
  • Sep 27, 1575

    Aristotle 384 B.C.

    Aristotle 384 B.C.
    According to aristotle he accepted the theory of Empedocles adding his own (incorrect) idea that the four core elements could be transformed into one another. The four elements being fire, water, earth and air.
  • Leucippius 5th Century B.C.

    Leucippius 5th Century B.C.
    According to Leucippius's theory, matter is composed of atoms seperated by empty space through which the atoms move.
  • Democritus 300B.C.

    Democritus 300B.C.
    Democritus's theory said that matter could not be divided into smaller and smaller pieces forever, eventually the smallest possible piece would be obtained. He named the smallest piece of matter "atomos," meaning "not to be cut."
  • Dalton's Atomic Theory 1808 A.D.

    Dalton's Atomic Theory 1808 A.D.
  • The War of 1812

    The war of 1812 was fought between 1812 and 1815 between The United States andreat Britian.
  • Mexican American War

    The Mexican-American War was fought between 1846-1848 and dramatically increased the United States.
  • American Civil War

    The Civil War was fought between 1861 and 1865, it focused on slavery and states rights.
  • J.J. Thomson 1897 A.D.

     J.J. Thomson 1897 A.D.
    JJ Thomson helped to change the modern view of the atom with the discovery of the electron through a series of experiments designed to study the nature of electric discharge. Thomson discovered the electron, and developed the raisin bread theory which stated that negatively charged electrons were suspended inside atoms of positively charged protons, much like raisins in raison bread.
  • Max Planck 1900

     Max Planck 1900
    Planck's law states that it is the basis of quantum theory, which states that the energy of electormagnetic waves is contained in indivisable quanta that have to be radiated or absorbed as a whole.
  • Ernest Rutherford 1911 A.D.

     Ernest Rutherford 1911 A.D.
    Rutherford descoveres that an atom has a small dense, positivly charged nucleus. Electrons are active and move throughout the nucleus.
    In addition Rutherford discovered the proton and was the first to create a nuclear reaction.
  • Niels Bohr 1913 A.D.

    Niels Bohr 1913 A.D.
    in order to study atomic structure, Bohr used Rtherfords model. He created a new modle that was used to show the chemical and physical properties of a atom.
  • WW1

    World War I was fought in 1914 and the battles ranged around the world.
  • Robert A. Millikan 1923 A.D.

    Robert A. Millikan 1923 A.D.
    Millikan's oil-drop experiment determined the charge and the mass of the electron.
    Bohr and Rydberg proved the most important proof of the new atomic theory, with help from these two numbers.
  • Louis de Broglie 1923

    Louis de Broglie 1923
    Louise developed the wave particle duality of nature theory. He also proposed a theory that moving particles have characteristics of waves.
  • Erwin Schrodinger 1926

    Erwin Schrodinger 1926
    Erwin developed a mathematical equation that described the motions of electrons in atoms. His wave equation proved Bohr;s orbit theory wrong. Schrodineger developed the Quantum Mechanical Model which determined how many energies an electron can have and how to estimate an electrons location.
  • Werner Heisenberg 1927

    Werner Heisenberg 1927
    Heisenberg created the Uncertainty Principal that states that it is impossible to know the position and momentum of a particle simultaneosly.
  • James Chadwick 1932

    James Chadwick 1932
    James proved the exicstence of the neutron. He proved that nuetrons have no charge and that the nuclei conatin both nuetrons and positvly charged protons. He produced hydrogen nuclear and nitrogen nuclear. He was awarded the Nobel Prize for Physics.
  • WW2

    World War II was fought between 1939-1945 and was the bloodiest war in history.