Postulates of Quantum Mechanics; Operators; The Harmonic Oscillator and the Rigid Rotator as models for vibrational and rotational transitions; Overview of H atom; Variational Method; Overview of He atom; SCF-LCAO-MO theory; Diatomics; Transition Dipole; Electronic spectroscopy; Frank-Condon principle; Spin transitions and Magnetic resonance. Bra-ket notation, Ehrenfest theorem, ladder operators, simple harmonic oscillator, and angular momentum operator.