The    numerical    values    assigned   for   ionicity/basicity of glasses, either calculated or experimentally determined, are not always in full agreement with actual facts and discrepancies among the theoretical ones are not unusual. For instance, SiO₂ is described by a single ionicity/basicity value even if the polymorphs of SiO₂ are, from this point of view, quite different. Unfortunately, this challenge did not get too many answers within the frame of present theories on ionicity/basicity concept.

   Present work deals with the study of nature of various chemical bondings and their distribution within the crystalline and vitreous oxides, respectively, with the same chemical compositions with that of crystalline compounds, based on original approach developed on electronic structure of crystalline solids. The possibility of decomposing complex chemical bondings into a sum of binary bondings, as suggested by Zhang, and its connection with electronic energy levels based ionicity, makes possible the evaluation of single bonds ionicity at local structural level. In this context, several results are given for unary glasses (SiO₂) and some crystalline compounds.