Atomic Theory Time line

  • 150

    Aristole 384- 322BC

    Aristole 384- 322BC
    Greek Philosopher whom argued that all mattere was made of Only four elements earth air water & fire for the next 2,000 years he overshadowed Democritus.
  • 200

    Democritus 460 - 370BC

    Democritus 460 - 370BC
    Greek philosopher Democritus proposed that all matter was made of small, unbreakable particles he called atoms, he thought atoms were to small to be seen. He used a beach as an example: far away it looks like a solid mass but close you can tell its made of small grains of sand.
  • 400

    Battle of Actium 31 BC

    Antony and Cleopatra defeated. Soon after, Augustus (Octavian) became 1st emperor of Rome.
  • 400

    Rutherford- Bohr model

    Rutherford- Bohr model
  • 500

    Atomic Planetary Model

    Atomic Planetary Model
  • May 13, 1000

    Plum Pudding Model

    Plum Pudding Model
  • May 13, 1110

    Small, Spherical, Indivisble solid model

    Small, Spherical, Indivisble solid model
  • Plan of Union

    William Penn proposes his Plan of Union, the earliest known attempt at unified government in the 13 Colonies.
  • Isaac Newton

    Proposed a mechanical universe with small solid masses in motion.
  • John Dalton

    in 1809 Dalton proposed the following:...
    1) all mater was made of neutral atoms.
    2) Atoms were solid spheres.
    3) Atoms of different elements differed in mass.
    4) atoms were indivisible and Indestructible.
    5) Atoms combine to form compounds.
  • Sir Wiliam Crookes

    Crookes constructed a glass tube with two metal plates inside it he removed almost all the air from the tube and sealed it when he connected the plates the + and - terminals of a high voltage battery he observed a mysterious glowing ray from experiments he was able to prove the ray was matter.
  • Wilhelm Roentgen

    Professor of physics in Worzburg, Bavaria was the First person to discover the possibility of using electromagnetic radiation to creat what we know as the xray.
  • Henri Becquerel

    Discovered radioactivity 1920
  • JJ Tohmson

    He discovered the Electron!
  • Robert Millikan

    Discovered the charge of an electrons in 1909
  • Dmitri Mendeleef

    Arranged elements into 7 groups with similar properties. He discovered that the properties of elements "were periodic functions of the their atomic weights". This became known as the Periodic Law.
  • Gilbert N. Lewis

    Gilbert N. Lewis
    American Physical Chemist known for the Discovery of the Covalent Bond
  • Marie Curie

    discovered Polonium in 1898
  • Frederick Soddy

    Frederick Soddy
    English Radiochemist, explained with Ernest Rutherfod that radioactivity is due to the transmution of elements he also proved the exstence of istopes of certain radio active elements he received the Noble Prize for Chem in 1922 & has a crater named for him on the far side of the moon.
  • Niels Bohr

    1913 proposed that electrons are arranged in up to 7 specific energy levels the arrangement of these electrons.
  • James Chadwick

    Discovered a 3-D subatomic particle in the atom called it the neutron because it was neutrul
  • Henri Becquerel

    While studying the effect of x-rays on photographic film, he discovered some chemicals spontaneously decompose and give off very pentrating rays.
  • Founding of Rome

  • 776 Legendary founding of Ancient Olympics

  • Werner Heisenberg

    Heisenberg, along with Max Brown and Pascual Jordan, set forth the matrix formulation of quantum mechanics in 1925
  • H.G.J. Moseley

    Using x-ray tubes, determined the charges on the nuclei of most atoms. He wrote"The atomic number of an element is equal to the number of protons in the nucleus". This work was used to reorganize the periodic table based upon atomic number instead of atomic mass.
  • WW1

    World War One Begins
  • de Broglie

    Discovered that electrons had a dual nature-similar to both particles and waves. Particle/wave duality. Supported Einstein.
  • James Chadwick

    Using alpha particles discovered a neutral atomic particle with a mass close to a proton. Thus was discovered the neutron.
  • Lise Meitner, Hahn, Strassman

    Conducted experiments verifying that heavy elements capture neutrons and form unstable products which undergo fission. This process ejects more neutrons continuing the fission chain reaction.
  • WW2

    ww2 begins
  • 1977-1978: US gives up panama canall

  • 9/11 Attack on New York and Washington.

  • US evades Iraq

  • 2009: President Obama elected into office.

  • Electrom cloud model

    Electrom cloud model