Duncan, Carl, and Clare Chemistry Timeline

  • 460 BCE


    Theorized the existence of the atom. Hated by many other Greek philosophers, and as a result, many of his works have not survived the test of time.
  • Antoine Lavoisier

    Discovered atomic conservation of mass, predicted the existence of silicon, and discovered the role oxygen plays in combustion. He also compiled the first semi-complete list of elements, helped develop the metric system, and named oxygen and hydrogen.
  • Joseph Louis Proust

    Proust’s Law/Law of Definite Proportions
    A compound always has a certain ratio of different elements, eg. Iron Disulfide always has a 2:1 ration of Sulfur to Iron
  • John Dalton

    Developed many modern ideas around atoms, including how atoms of the same type combine to make elements, and atoms of different elements combine to make compounds
  • Michael Faraday

    2 laws of Electrolysis
    1 The amount of chemical deposition is proportional to the quantity of electricity that passes in solution
    2 The mass of different substances deposited by the same quantity of electricity are proportional to their chemical or equivalent weights
  • Antoine Henri Becquerel

    Discovered radioactivity in 1896 after experimenting with uranium salts and x-ray light. Also worked with the Curries and received a Nobel prize with them
  • J.J. Thomson

    J.J. Thomson
    Discovered the electron in 1897 by experimenting with cathode rays. In 1904 he proposed the “Plum Pudding” model, where an atom is composed of a positively-charged sphere and negatively-charged particles are embedded within like raisins in a plum pudding.
  • Max Planck

    Max Planck
    Studied quantum theory and black body radiation. He also discussed and had a changing opinion on Einstein’s theory of relativity.
  • Marie and Pierre Curie

    They both researched radioactivity, and Marie was the first woman to win a Nobel prize and is the only person to win two Nobel prizes in two different fields. She coined the term radioactivity and won a Nobel prize in physics for this research along with Pierre Curie and Henri Becquerel. Marie discovered polonium and radium after Pierre died, and won a Nobel prize in chemistry for this.
  • Robert Millikan

    Discovered the precise measures of elementary charge, the electric charge carried by singular protons and electrons. This was done by suspending small droplets of oil between two electrodes, and finding the electric field.
  • Ernest Rutherford

    Ernest Rutherford
    Discovered radioactive half-life, the element radon, and alpha and beta radiation, he received a Nobel prize in chemistry for this work. He also made the first man-made nuclear reaction and discovered the proton.
  • Lise Meitner

    Provided evidence for nuclear fission with Otto Hahn, he won the Nobel Prize for chemistry but she was ignored
  • Albert Einstein

    Mathematically proved the existence of atoms through the movement of particles in a liquid. Einstein’s calculations also allowed us to find the size of atoms and molecules.
  • Niels Bohr

    Niels Bohr
    Developed the Bohr atomic model, which mainly proposed the idea of energy levels. While the model is today outdated, many of its main principles remain relevant today.
  • James Chadwick

    Discovered neutrons in 1932 after bombarding beryllium atoms with alpha particles. He determined that the radiation given off had a neutral charge and a similar mass to protons.
  • Wolfgang Pauli

    Pauli Exclusion Principle, no 2 electrons in an atom or molecule can have the same 4 quantum numbers
  • Wolfgang Pauli

    Discovered the “Exclusion Principle” in 1924, which states that no two fermions (including electrons and protons) can simultaneously exist in the same quantum state.
  • Maria Goeppert-Meyer

    Maria Goeppert-Meyer
    Created Nuclear Shell Model, protons and neutrons form shells inside the nucleus like electrons. Explains why nuclei with certain number of protons and neutrons are more stable
  • Harold Evans

    Worked on nuclear fission projects for the Manhattan Project, which produced the first atomic bombs
  • J. Ernest Wilkins Jr.

    Worked on the Manhattan Project, created Wigner-Wilkins approach for estimating the distribution of neutron energies within nuclear reactors with Eugene Wigner
  • Murray Gell-Mann

    Created “Eightfold way” scheme, which organized subatomic particles, discovered quarks and gluons