Atomic Timeline

By 28bend
  • 440 BCE

    Plato

    Plato
    Theorized that solid forms of matter are composed of indivisible elements shaped like triangles.
  • 400 BCE

    Democritus

    Democritus
    The atom was the basic building block of matter.
  • 330 BCE

    Solar System Model

    Solar System Model
    Illustrate the relative positions and motions of the planets and moons.
  • 700

    The Alchemists

    The Alchemists
    Developed the theory that all metals were formed of sulfur and mercury.

  • Robert Boyle

    Robert Boyle
    He demonstrated that matter is made up of tiny particles that he called corpuscles.

  • Antoine Lavoisier

    Antoine Lavoisier
    Matter was composed of atoms that were not created or destroyed during chemical reactions.

  • Billiard Ball Model

    Billiard Ball Model
    Defined an atom to be a ball-like structure as the concepts of atomic nucleus and electrons were unknown.

  • John Dalton

    John Dalton
    All matter was compromised of invisible and indestructible atoms with distinct masses and properties.

  • Dmitri Mendeleev

    Dmitri Mendeleev
    Invented the periodic table.

  • Amedeo Avogadro

    Amedeo Avogadro
    Two hypotheses - Equal volumes of gas contain equal numbers of molecules; Elementary gases were composed of two atoms.

  • Pierre and Marie CUrie

    Pierre and Marie CUrie
    Discovered the radioactive elements polonium and radium.

  • JJ Thompson

    JJ Thompson
    All atoms contain tiny negatively charged substance particles or electrons.

  • Plum Pudding Model

    Plum Pudding Model
    Depicts the electrons as negatively charged particles embedded in a sea of positive charge.

  • Albert Einstein

    Albert Einstein
    Mathematically proved the existence of atoms.

  • Robert Millikan

    Robert Millikan
    Accurate determination of the charge carried by an electron.

  • Ernest Rutherford

    Ernest Rutherford
    Described the atom as having a tiny, dense, and positively charged core called the nucleus.

  • Niels Bohr

    Niels Bohr
    Proposed a theory for the hydrogen atom based on quantum theory.

  • Henry G J Mosely

    Henry G J Mosely
    The atomic number of an element is the number of positive charged in the atomic nucleus.

  • Werner Heisenburg

    Werner Heisenburg
    Developed an idea that a strong force in the nucleus holds the neutrons and protons together.

  • Electron Cloud Model

    Electron Cloud Model
    Represents the area around an atom's nucleus where electrons are most likely to be found.

  • James Chadwick

    James Chadwick
    Discovered the neutron.