Thomson's Atomic Model | Structure of an atom Discovery of Electron Discovery of Proton Rutherford's Atomic Model, Chemistry Bohr's Atomic Model | Chemistry Atomic Spectrum and Hydrogen Spectrum Absorption Spectrum and Emission Spectrum Planck's Quantum Theory | Chemistry De Broglie Hypothesis | De Broglie Wavelength Dual Nature of Light Heisenberg Uncertainty Principle Quantum Numbers | What are the 4 Quantum Numbers? Chemistry Aufbau Principle | Chemistry Hund's Rule | Chemistry Complete Electronic Configuration |Aufbau Principle | Hund's Rule | Pauli Exclusion Principle Photoelectric Effect | Einstein's Photon Theory