PECULIARITIES OF ACID-BASIC PROPERTIES OF SILICON AND GERMANIUM OXY-COMPOUNDS

Abstract

Peculiarities of the change of acid-basic properties of Silicon and Germanium oxy-compounds as a function of the position of elements in the periodic system are established. It is stated that Germanium dioxide possesses much lower (compared to SiO2 and SnO2) temperatures of melting and boiling as well as lower surface tension and dynamic viscosity. This fact points out more income of the molecular structure, hence, more expressed acidic properties. The higher value of the constant of acidity of the aqueous solution of GeO2 (i.e. H2GeO3) in comparison with H4SiO4 confirms the above mentioned. Systems of the GeO2 – MxOy type, where M – metal, exhibit more chemical diversity compared to the analogous systems on the basics of SiO2. For example, GeO2 forms rather stable ternary compounds with Ga2O3 or CeO2, but SiO2, contrary, does not. At the same time, compounds of SiO2 with P2O5 are much stronger, than analogous compounds of GeO2. This fact means that SiO2 has more basic properties than GeO2. Unfortunately we have no other quasi-binary systems of SiO2 or GeO2 with more acidic oxides for the comparison. The sum of these data indicates on the more expressed acidic and less expressed basic properties of GeO2 versus SiO2, which is an additional confirmation of the “Silicon – Germanium anomaly” in the series of elements of the IV group of the periodic system. This phenomenon, probably, is caused by completion of the previous 3d – electronic level in an atom of Germanium. So, some resemblance between Si–Ge and Al–Ga pairs of elements takes place.