Chemistry Timeline

  • John Dalton

    Dalton created the following laws:
    1. Law of Multiple Proportions - If 2 elements together form more than one compoud, then the ratio of the masses of the second element which combine with a fixed mass of the first will be radios of small whole numbers.
    2. Law of Definite Composition - A compound always contains two or more elements combined in a definite proportion by mass.
    3. Law of Conservation of Mass - The mass of a closed system completely isolated will remain constant overtime.
  • J.J. Thomson

    Thomson discovered the electron, and developed the raisin bread theory which stated that negatively charged electrons were suspended inside atoms of positively charged protons, much like raisins in raison bread.
  • Max Planck

    Planck develops Quantum Theory, which explains on the smallest scale by looking at the structure and behavior of the atoms and subatomic particles. In addition, created the Wave/Particle Duality theory using waves and particles to explain properties of light.
  • Hontaro Nagaoka

    Nagaoka created a model of the atom based of the rings of Saturn. His idea led to the question of electrons losing energy as they move. To prove his model, he had to prove that the electrons were in fact NOT losing energy as they moved. Later, Earnest Rutherford and Bohr's research agreed with this idea.
  • Period: to

    Robert Millikan

    Millikan performed the Oil Drop Experiment, which was used to study and find the size of an electron. The experiment involed spraying oil into a chamber that had a positive and negative charge, then changing the atoms in the oil to a negative charge so they'd be suspended in mid-air. This isolated the drops and made it possible for the atoms to be measured.
  • Ernest Rutherford

    Rutherford discovered the the atomic nucleus, and developed an atomic model. In addition, Rutherford discovered the proton and was the first to create a nuclear reaction.
  • Niels Bohr

    Used Rutherford's atomic model as a guide to study atomic structure. He created a new model that was used to show the physical and chemical properties of the atom. While this model is now considered innacurate, it is used to teach chemical properties of atoms to students.
  • Louis De Broglie

    Developed the Wave Particle Duality of Nature theory, stating that all matter (not just light) has wave properties.
  • Werner Heisenberg

    Heisenberg creates his Uncertainty Principle, stating that one cannot be certain of all sub-atomic particles' principles at the same time, only a probability. Because while measuring one aspect, you alter others, you cannot know every principle.
  • James Chadwick

    Proved the existence of th neutron through Nuclear science. Awarded the Nobel Prize for Physics. Chadwick produed hydrogen nuclear and nitrogen nuclear. He found the velocity of these atoms, then smashed an alpha particle into a metallic element. This released radiation which was aimed into wax. The radiation hit the hydrogen atoms that were in the wax, and Chadwick took the wax into a detecting chamber and discovered massive nuetral particles.
  • Erwin Schrodinger

    Schrodinger discovered his wave equation, which refuted Bohr's orbit theory. Developed the Quantum Mechanical Model (QMM) which determines the allowed energies an electron can have, and how to estimate the electron's location.