History of the Atom

  • Antoine Lavoisier

    Antoine Lavoisier
    Called the "Father of Modern Chemistry" Lavoisier made proved the law of conservation of mass. He also discovered that water is made up of Hydrogen and Oxygen, and he also showed that Graphite and Diamonds were both made of Carbon by buring them to make Carbon Dioxide.
  • John Dalton

    John Dalton
    Dalton came up with is Law of Multiple Proportions. He also came up with the concept of a mole. He later proposed a system of symbols that could be used to represent different atoms. He repectivly asigned Hydrogen with the atomic number 1. He came up with the Atomic Theory of Matter and represented the Atom as small spheres that were undivisible.
  • Henri Becquerel

    Henri Becquerel
    While investigating phosphorescence he discovered radioactivity by accident. He accidentally discovered the property while working on try to discover if there was a link between phosphorescence and x-radiation. He showed that the atom was neither indivisible nor immutable.
  • J.J. Thomson

    J.J. Thomson
    Thompson came up with a new improved version of Dalton's sphere representation. He described his atom as a plum-pudding like model with negetive particles inbedded inside the a sphere if positive matter. His theory challenged Dalton's by saying that there were things smaller than a atom and rather than just a sphere, it also had other materials inbedded into it.
  • Marie & Pierre Curie

    Marie & Pierre Curie
    Marie & Pierre Curie pioneered the study of radioactivity along with its discoverer Henri Becquerel their study led them to the discovery of the elements radium and polonium. Due to the extensive work they did on the nucleas of the atom, they led the way to the modern understanding of releasing trmendous energy by spliting an atom. Marie also researched what medical applications radioactive materials had.
  • Ernest Rutherford

    Ernest Rutherford
    Rutherford proposed that instead of all the positive matter being a solid sphere, it was rather a smaller ball inside the atom with the negetive charged particles around it. His model was derived while he was trying to prove Thomson's model by firing alpha particles at a sheet of gold. He was Thomson's student.
  • Max Planck

    Max Planck
    Invented the quantom theory and also came up with a new essential constant know as Planck's constant that can be used to calculate the energy of a photon. He also came up with the law of heat radiation (Planck's law of black body radiation) which is the basis of quantom theory.
  • Robert Millikan

    Robert Millikan
    Millikan discovered the unit charge of an electron, This allowed for calculations of the mass of the elctrons and also the positively charged atoms. (e = 1.60 x 10^-19).
  • Henry Moseley

    Henry Moseley
    Moseley dicovered that the enery of the x-rays that are given off by elements decrease linearly with each element on the periodic table. He later proposed that this was due to the positive charge of the nucleas and came up with a function to represent it. He later also rearranged the periodic table based on their atomic numbers rather than the atomic mass. Studied under Rutherford.
  • Niels Bohr

    Niels Bohr
    Came up with a new model that showed the electrons were orbiting the nucleaus. In his model, he came up with bohr proposed special orbits and that the electrons were not just oprbiting at random. The orbits of atoms were based entirely on their energy. Each level of energy could hold a different number of electrons, represented by the equation (2n^2) where n is what level of energy it is. Student of Rutherford.
  • Erwin Schrodinger

    Erwin Schrodinger
    Pioneered wavemechanics, Also came up with the now famous wave equation. He also proposed that electrons moved in a wave-lke behavior and that their exact position could not be found. He divided the layers of the electron shells into subshells with each subshell holding 2 electrons and each different layer of the shell has different amounts of subshells for example; 1st shell has 1 subshell, 2nd=2, 3rd=3.
    Succeeded Max Planck as the chair of theoretical physics at the University of Berlin.
  • Werner Heisenberg

    Werner Heisenberg
    He developed quantum mechanics, he is best known for his uncertainty principle which states that you cannot measure both the velocity and momentom of a atom at the same time. So this means that we can never know the exact position of an electron at any given time.
  • James Chadwick

    James Chadwick
    Chadwick discovered the neutron, his discovery led to the discovery of nuclear fission, which then led to the discovery of the nuclear bomb. His dicovery was found when he and rutherford studied the properties of atom and found that the atomic number was consitantly smaller than the atomic mass. Which lead him to the neutron. Worked under Rutherford.
  • Aristotle

    Aristotle disagreed with the theories of the time he could not see how the atoms could stay in motion inside of a void, Instead, he thought of a theory based on the 4 elements. Aristotle's model also had 2 forces conflict and harmony which kept the elements in their proper place.
  • Democritus

    Created an hypothesis stating that all matter was made up of small indestructable parts known as atoms. He proposed that the atoms themselves remain unchanged, however, they shift around in space to form different objects. His idea is behind modern physics.