This is the completely revised enlarged and updated edition of the textbook in three volumes aimed at the honors and postgraduate students. In a logical sequence the book deals extensively with different aspects such as atomic structure (both classical and wave mechanical) and atomic spectra fundamentals of quantum mechanics and wave mechanics nuclear chemistry and radiation chemistry different theories of valence forces and chemical forces band and Bloch theory of solids solid state chemistry supramolecular chemistry acids and bases nonaqueous solvents and redox potentials. It also covers the different aspects of materials science which is emerging with a great promise.