atomic theory timeline

Timeline created by reese.enderlein
  • -500 BCE

    ancient greece's

    ancient greece's
    Democritus was one of the first atomic theorists and had an extremely remarkable atomic theory that still relates to today's chemistry. Democritus believed that if you break a rock in half, both halves would be made of the same material. if you break the rock into smaller and smaller pieces eventually it becomes so small that it can't be divided and he called it an atomos which translates to indivisible.
  • -384 BCE


    Alchemy is the origin of chemistry and was created by the philosopher Aristotle, in which he believed that everything was made up of the four elements earth, air, fire, and water. alchemy was focused on goals like turning base metals into gold and discovering the elixir of life which would grant health, wealth, and immortality. although their work was not based on real science they were still able to discover a lot in the field of atomic theory.
  • John Dalton

    John Dalton
    Daltons contributions to atomic theory is his theory that atoms are indivisible and the building blocks of matter. with the atoms being identical among the same element but different sizes and masses between different elements.
  • J.J.Thomson

    Thomson discovered the electron and created a new model of the atom that included the charged particles within the atom. he related the model to plum pudding, with the raisins being the electrons and the pudding containing a positive charge, failing to recognize positive charges as a particle.
  • Max Planck

    Max Planck
    Plank discovered that the frequency of a wave is equal to the energy, as well as discovering was quantized.
  • Albert Einstein

    Albert Einstein
    Einstein mathematically proved the existence of the atom which made it so that one could determine the size of an atom. he also discovered that liquids are made up of molecules that are in random motion and was able to find the rate they move at.
  • Ernest Rutherford

    Ernest Rutherford
    Rutherford greatly improved the model of the atom. his model has a positively charged nucleus surrounded by empty space with very small electrons moving in that surrounding space of the nucleus. he also discovered the proton and hypothesized what was later discovered as the neutron.
  • Niels Bohr

    Niels Bohr
    Bohr discovered that electrons in their orbitals can move up an orbital to a new energy level.
  • Louis de Broglie

    Louis de Broglie
    Louis de Broglie discovered that electrons don't only act like a particle but have a duality of also acting as a wave.
  • Wolfgang Pauli

    Wolfgang Pauli
    Pauli discovered the spin of electrons with either a spin-up or a spin down. along with this, he discovered that no two electrons can be in the same quantum state.
  • Werner Heisenberg

    Werner Heisenberg
    Werner extended the work Schrodinger did by discovering how to find not only the position of the electron but the momentum of the electron as well.
  • Erwin Schrödinger

    Erwin Schrödinger
    Schrodinger used math to find the likely hood of the position that the elections are. his model is portrayed as electron clouds surrounding the nucleus.
  • James Chadwick

    James Chadwick
    Chadwick discovered the neutron which is a chargeless particle located in the nucleus. the stability of an atom is reliant on the balance of protons and neutrons which makes his discovery crucial in the discovery of nuclear fission.
  • Richard Bader

    Richard Bader
    Bader made large contributions in explaining the behavior of atoms in the molecule. This theory went against accepted theories because he believed that there are no orbitals which made it hard to publish.
  • Robert Le Roy

    Robert Le Roy
    Le Roy's theory explains the quantitative measurement and properties of the forces in molecular systems.