The History of the Atomic Theory

  • Antoine Lavoisier- First Law of Conservation of Mass

    Matter cannot be created or destroyed
  • Joseph Louis Proust- Law of Definite Proportions

    This says if you break down a compound to its elements, those elements will always exist in a set ratio
  • John Dalton- Law of Multiple Propportions

    elements react with one another in ratios of small integers. From this Dalton was able to conclude a first list of relative atomic weights according to the mass ratios in which they combined.
  • Amedeo Avogadro- Avogadro's Law

    This law states that any two ideal gases at STP and same volume contain the same number of molecules. This allowed him to ultimately estimate more accurately atomic masses of various elements
  • J.J. Thompson- Discovery of Electrons

    Discovered the electron through use in a cathode ray tube. When cathode rays were both affected by magentism and electricity, he concluded there were negantively charged particles
  • Ernest Rutherford- Discovery of the Nucleus

    Nucleus was proved to exist by shooting alpha particles at gold foil. Most of the particles went straight through the foil, but a small percentage of them bounced off the nucleus
  • Niels Bohr- Bohr Model of the Atom

    Quantum theory is emerging, and Niels Bohr used ideas of energy as quanta to determine electron orbitals and energies
  • Rutherford- Discovery of Protons and Neutrons

    experiment with alpha particles through nitrogen emitted hydrogen nuclei
  • Erwin Schrodinger-Schrodingers equation, Heisendberg Uncertainty Principle

    Schrodinger brought forth the idea that subatomic particles can exhibit a degree of wavelike function. This filled in several gaps of Bohr's model, but also opened up many new questions and critiques. Ultimately scientists took ideas from both models and also came up with the Heisenberg Uncertainty Principle which states that an electron's position and momentum cannot be simultaneously observed