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Double Slit Experiment conducted
Thomas Young conducts the double-slit experiment with light -
John Dalton formalises "Atom"
John Dalton held that all the atoms of an element are identical, of the same size and weight -
Discovery of spectral lines
The German optician Joseph von Fraunhofer independently discovered spectral lines -
Balmer Lines verified mathematically
Johann Balmer finds a mathematical expression for observed hydrogen line wavelengths -
Photoelectric Effect discovered
Heinrich Hertz discovers the photoelectric effect -
Radioactivity discovered
Antoine Becquerel discovers the radioactivity of uranium -
Discovery of the Electron
Emil Wiechert, Walter Kaufmann and J.J. Thomson discover the electron -
Nucleus discovered
Rutherford conducted the Gold foil experiment to come up with the Rutherford model of the atom -
Quantum mechanical explanation of the Atom
Niels Bohr presents his quantum model of the atom -
Pauli Exclusion principle and Magnetic spin
Wolfgang Pauli states the quantum exclusion principle for electrons -
Discovery of the Neutron
James Chadwick discovers the neutron