This book is intended primarily for undergraduate students in basic and applied sciences in the fields of material sciences, technological sciences, natural and life sciences and medical sciences.It describes in a pedagogical way: the chemical bond through the different theories: the Lewis model, the VSEPR method, the theory of hybridization and the overlaps of atomic orbitals as well as the theory and the energy diagrams of molecular orbitals. Intermolecular bonds, polarity and magnetism of molecules, as well as the solid state through the study of cohesive forces in the different types of crystals, systems, networks and structures of crystal structures are also well developed in this manual.