The crucial experiments showing the failure of classical physics in explaining the properties of matter and radiation The postulates of quantum mechanics. Wave particle duality and the uncertainty relation.The time dependent and time independent Schrödinger equation. Symmetry and conservation laws. Basic features of the quantum mechanical world explored through one-dimensional problems: the harmonic oscillator, the square well and barrier, free and bound states. Energy quantization. Tunnelling. One dimensional periodic potentials, energy bands and band gaps.