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John Dalton
[http://www.chemheritage.org/discover/chemistry-in-history/themes/the-path-to-the-periodic-table/dalton.aspx](chemharitage.org)Dalton calculated atomic weights from percentages of compositions of compounds, using an arbitrary system to determine the likely atomic structure of each compound. Dalton also came to believe that the particles in different gases had different volumes and surrounds of caloric, thus explaining why a mixture of gases—as in the atmosphere—would not simply layer out but was kept in constant motion. Dalton consolidated his theories in his New System of Chemical Philosophy. -
The Invention of the Electro Magnetd
http://www.columbia.edu/itc/chemistry/chem-c257/navbar/Hans Christian Oersted was a scientists whos main focus was electric currents. He figured out that when electric currents are passed through a wire, a magnetic field is created. He wrapped a coil of wire around a solid making the solid a core. -
The Proton Discovery
http://www.columbia.edu/itc/chemistry/chem-c257/navbarEugene Goldstein discovered positive particles by using a tube filled with hydrogen gas. The positive particle had a chare egual and opposite to the electron. It also had a mass of 1.66E-24g or one atomic mass unit. The positive particle was named the proton -
The Invention of the X-Ray
Wilhelm Roentgen accidentally discovered X-Rays while researching the glow produced by cathode rays. He discovered that the rays that were causing the flouresence could also pass through glass, cardboard, and walls. The rays were called X-Rays. -
Thomson
http://www.chemheritage.org/discover/chemistry-in-history/themes/atomic-and-nuclear-structure/thomson.aspxdiscovered the electron in a series of experiments designed to study the nature of electric discharge in a high-vacuum cathode-ray tube, an area being investigated by numerous scientists at the time. Then in 1904 Thomson suggested a model of the atom as a sphere of positive matter in which electrons are positioned by electrostatic forces. -
Rutherford
http://www.rsc.org/chemsoc/timeline/pages/1911.htmlRutherford discovered the atom as having a central positive nucleus surrounded by negative orbiting electrons. This model suggested that most of the mass of the atom was contained in the small nucleus, and that the rest of the atom was mostly empty space. -
The Discovery of the Three Types of Radio Activity
Ernest Rutherford sent a radio active source through a magnetic field. Some of the radio activity was deflected to the positive plate; some of it was deflected to the negative plate; and the rest wewnt through the magnetic field without deflection. Therefore, there were three types of radio activity discovered: Alpha Particles(+0), Bata Particles(-), and Gamma Rays(neutral). -
Bohr
http://www.rsc.org/chemsoc/timeline/pages/1913.htmlBohr discovered that electrons travel in stationary orbits defined by their angular momentum. This led to the calculation of possible energy levels for these orbits and the postulation that the emission of light occurs when an electron moves into a lower energy orbit. -
The Neutron and Discovery of Nuclear Fission
Because of James Chadwick discovering the Neutron, Enrico Fermi bombards elements with neutrons and produces elements of the next highest atomic number. Nuclear Fission occured when Fermi bombarded Uranium with neutrons.
