Atomic timeline

  • The Alchemists
    500 BCE

    The Alchemists

    They believed all metals are composed of mercury and sulfur and that it is possible to change base metals into gold.
  • Democritus
    400 BCE

    Democritus

    He theorized that all material bodies are made up of indivisibly small atoms. He introduced the idea of the atom as the basic building block of matter
  • Plato
    387 BCE

    Plato

    He found that there are 5 solid shapes whose sides are made from regular polygons and was convinced that atoms of matter acquire from from these 5 fundamental solids.
  • Robert Boyle

    Robert Boyle

    Believed that chemical experiments could demonstrate the truth of corpuscularian philosophy. He created the idea of a element
  • Antone Lavoisier

    Antone Lavoisier

    He found that the total mass of products and reactants in a chemical reaction is always the same. Total mass=reactants in chemical reactions
  • John Dalton

    John Dalton

    He believed all matter was composed of atoms indivisible and indestructible building blocks. Also believed all compounds were composed of combinations of these atoms in defined ratios
  • Billiard Ball Model

    Billiard Ball Model

    This model was created by John Dalton and stated that elements consisted of tiny particles called atoms. Also stated that all the atoms that make up the element have the same mass.
  • Amadeo Avagadro

    Amadeo Avagadro

    He hypothesized that equal volumes of gas contain equal number of molecules and also hypothesized that elementary gases like oxygen, hydrogen, or nitrogen were composed of 2 atoms.
  • Dmitri Mendeleev

    Dmitri Mendeleev

    He devised the periodic classification of the chemical elements and invented the periodic table.
  • JJ Thomson

    JJ Thomson

    He determined the existence of a electron and figured out that the particles that make up the rays were 1,000 times lighter than the lightest atom.
  • Pierre and Marie Curie

    Pierre and Marie Curie

    They discovered the radioactive elements polonium and radium.
  • Plum Pudding Model

    Plum Pudding Model

    The model was proposed by JJ Thomson. The model explained 2 properties of atoms that are known: that electrons are negatively charged particles and that atoms have no net electric charge.
  • Albert Einstein

    Albert Einstein

    He mathematically proved the existence of atoms and said that any liquid is made up of molecules.
  • Ernest Rutherford

    Ernest Rutherford

    He discovered that there are 2 types of radiation, alpha and beta particles. Also figured out that atoms consist mostly of empty space with its mass concentrated on the nucleus.
  • Solar System Model

    Solar System Model

    This model is created by Ernest Rutherford and describes an atom as a central massive positive entity and orbiting around it, the negative entities.
  • Neils Bohr

    Neils Bohr

    First one to say there was electrons outside the nucleus. Also the first to discover that electrons travel in separate orbits.
  • Robert Millikan

    Robert Millikan

    He discovered that there is a fundamental electric charge which is the charge of an electron. He figured out what the accurate determination of a charge carried by a electron.
  • Henry G.J. Mosely

    Henry G.J. Mosely

    He discovered that the atomic number is the number of positive charges in the nucleus.
  • Werner Heisenberg

    Werner Heisenberg

    He discovered the uncertainty principle which states that a particles position and momentum cannot both be known exactly
  • Erwin Schrodinger

    Erwin Schrodinger

    He used mathematical equations to describe the likelihood of finding a electron in a specific position and he created the quantum mechanical model.
  • Electron Cloud Model

    Electron Cloud Model

    A model of an atom in which the atom consists of a small but also giant nucleus surrounded by a cloud of rapidly moving electrons. This model was created by Erwin Schrodinger
  • James Chadwick

    James Chadwick

    He discovered the neutron.