atomic timeline

  • Plato
    427 BCE

    Plato

    He theorizes that these solid forms of matter are composed of indivisible elements (thecollecter.com)
  • Democritus
    400 BCE

    Democritus

    He theorized that all material bodies are made up of indivisibly small atoms (britamica.com)
  • The Alchemists
    300 BCE

    The Alchemists

    The Alchemists believed that all metals here formed from 2 principles such as mercury and sulfer (uwaterloo.com)
  • Solar System Model
    230 BCE

    Solar System Model

    Where the sun is the center of the universe (education.com)
  • Robert Boyle

    Robert Boyle

    He demonstarted that matter is made of tiny particles that he called corpuscle, but that are known as atoms today. (study.com)
  • Antone Lavoisier

    Antone Lavoisier

    He defined the law of conversation of mass (study.com)
  • John Dalton

    John Dalton

    He suggested that all matter was comprised of indivisible and indestructible atoms with district masses and properties (royalsociety.com)
  • Billiard Ball Model

    Billiard Ball Model

    This defined an atom to be like a ball-like structure (ck12.org)
  • Amedeo Avogadro

    Amedeo Avogadro

    He realized that equal volumes of gas contain equal numbers of molecules and that elementary gasses such as hydrogen, nitrogen, and oxygen were composed of two atoms (lemoyne.edu)
  • Dmitri Mendeleev

    Dmitri Mendeleev

    He discovered what is called the periodic table (khanacademy.org)
  • JJ Thompson

    JJ Thompson

    He proposed the plum pudding model of the atomy which had negatively-charged electrons embedded within a positively charged soup (khanacademy.org)
  • Pierre and Marie Curie

    Pierre and Marie Curie

    They discovered the strongly radioactive elements polonium and radium (Briannica.com)
  • Electron Cloud Model

    Electron Cloud Model

    The area around an atom's nucleus where electrons are most likely to be found (universetoday.com)
  • Plum Pudding Model

    Plum Pudding Model

    The atom is a sphere of positive charge and negatively charged electrons are embedded in it to balance the total positive charge (britannica.com)
  • Albert Einstein

    Albert Einstein

    He mathematically predicted the size of both atoms and molecules (ck12.com)
  • Robert Millikan

    Robert Millikan

    He accurate determination of the charge carried by an electron, using the elegant falling-drop method (nobelrpize.org)
  • Ernest Rutherford

    Ernest Rutherford

    He established that the mass of the atom is concentrated in it's nucleus (primaryconnections.org)
  • Nelis Bohr

    Nelis Bohr

    He proposed a theory for the hydrogen atom, based on quantum theory that some physical quantities only take discrete values (nobleprize.org)
  • Henry G. J. Mosely

    Henry G. J. Mosely

    He arranged the elements in the periodic table accordingly to atomic number (study.com)
  • James Chadwich

    James Chadwich

    He discovered that atoms consisted not only protons and electrons but also neutrons (study.com)