C atom e1

Atomic Theory and Atomic Model

By Sling
  • 384

    Aristotle (384-322 BC)

    Aristotle (384-322 BC)
    Aristotle proposed that all matter consisted of four elements: earth, air, water, and fire. He also proposed that all matter consisted of four qualities: dryness, hotness, coldness, and wetness.
  • 384

    Aristotle diagram

    Aristotle diagram
  • Period: 384 to

    Atomic theory and Atomic Model Timeline

  • 460

    Democritus (460-370 BC)

    Democritus (460-370 BC)
    Democritus was the first philosopher to propose the existance of the atom calling it the atomus.
  • 500

    Alchemists (500 BC- 1720)

    Alchemists (500 BC- 1720)
    Discovered that metals can be changed onto other substances making them study the particles of metals which led to the atom.
  • Benjamin Franklin

    Benjamin Franklin
    Proposed that matter has positive and negative charges from his stormy kite flight attached with a metal key experiment.
  • Stormy Kite flight

    Stormy Kite flight
  • Antoine Lavoisier

    Antoine Lavoisier
    Discovered the law of Conservation of Mass.
  • Joseph Proust

    Joseph Proust
    Developed the Law of Constant Composition which is the law that mass cannot be gained or depleted through a reaction or experiment.
  • John Dalton

    John Dalton
    John Dalton proposed that matter has positive and negative charges.
  • Michael Faraday

    Michael Faraday
    Michael Faraday developed the Laws of Electrolysis which is splitting molecules with electricity.
  • Electrolysis Experiment

    Electrolysis Experiment
  • Dmitri Mendeleev

    Dmitri Mendeleev
    Dmitri Mendeleev discovered the Periodic Law which help build the periodic table and the formula for atoms
  • William Crookes

    William Crookes
    William Crookes discovered cathode rays are deflected by electric fields and magnets suggesting a negative charge.
  • Cathode Ray Tube

    Cathode Ray Tube
  • G.J. Stoney

    G.J. Stoney
    G.J. Stoney proposed that electricity was made of discrete negative particles he called electrons.
  • Henry Becquerel

    Henry Becquerel
    Discovered radioactivity.
  • J.J. Thomson

    J.J. Thomson
    J.J. Thomson discovered the charge to mass ration of an electron using the Cathode Ray Tube Experiment. This discovery also helped him create the Plum Pudding Model.
  • Cathode Ray Tube Experiment

    Cathode Ray Tube Experiment
  • Plum Pudding Model

    Plum Pudding Model
  • Marie & Pierre Curie

    Marie & Pierre Curie
    Marie & Pierre Curie discovered that radiation breakes down particles spontaneously which released subatomic particles and radiation in the form of energy.
  • Max Planck

    Max Planck
    Max Planck used the idea of discrete units of energy to explain hot glowing matter. He called these discrete units of energy quanta.
  • Hantaro Nagaoka

    Hantaro Nagaoka
    Hantaro Nagaoka created the Saturnian Model which has flat rings of electrons revolving around a positively charged particle.
  • Saturnian Model

    Saturnian Model
  • Albert Einstein

    Albert Einstein
    Albert Einstein developed the equation for for energy which is mass times speed of light squared.
  • Equation of Energy

    Equation of Energy
  • Robert Millikan

    Robert Millikan
    Robet Millikan determined the charge and mass of an electron through the Oil Drop Experiment.
  • Oil Drop Experiment

    Oil Drop Experiment
  • Ernest Rutherford

    Ernest Rutherford
    Ernest Rutherford found that the positive charge and mass of the atom occupied a small volume in the center and the rest was empty space through the Gold Foil Experiment.
  • Gold Foil Experiment

    Gold Foil Experiment
  • Henry Moseley

    Henry Moseley
    Henry Moseley discovered the atomic number which is the number of protons in an element.
  • Francis Aston

    Francis Aston
    Francis Aston discovered isotopes.
  • Niels Bohr

    Niels Bohr
    Created the Bohr Model
  • Bohr Model

    Bohr Model
  • Louis de Broglie

    Louis de Broglie
    Louis de Broglie discovered that electrons had a duel nature similar to particles and waves.
  • Werner Heisenberg

    Werner Heisenberg
    Discovered the Principle of Indeterminancy.
  • Erwin Schrodinger

    Erwin Schrodinger
    Erwin Schrodinger discovered the electron cloud.
  • Electron Cloud

    Electron Cloud
  • James Chadwick

    James Chadwick
    Discovered neutrons in the nucleus giving the world the third atomic particle.
  • Neutron