Some Toxic Effects of Vanadium Pentoxide

Abstract

Chemistry Vanadium is a silvery-white metal of specific gravity 5-96, melting-point 1710? C, atomic weight 50-95, atomic volume 9-3, and atomic number 23. The name is derived from that of the Scandinavian goddess Vanadis (Parkes and Mellor, 1939). It is rarely encountered in its pure state owing to difficulties in production consequent upon its tendency to oxidation. In Mendel?ef's Periodic Table the atomic number of 23 places it in the A Sub-Group of Group V, with niobium, tantalum and proactinium. The last-named substance has radio-active properties. From the electronic con figurations of the atoms in members of this sub group it is evident that they are transition elements, since the penultimate electron group is incomplete and is in process of filling up. As transition elements, they are characterized by very variable valencies, the formation of highly coloured ions, are paramagnetic and have marked catalytic power. Four oxides are known: hypovanadous oxide (VO or V202), vanadous oxide or vanadium tri oxide (V2?3), hypovanadic oxide (V02 or V204) and vanadic oxide or vanadium pentoxide (V205). Hypovanadous oxide is a black powder. With acids it produces lavender-coloured solutions of hypovanadous salts from which caustic alkalies precipitate hypovanadous hydroxide, V(OH)2, one of the most powerful reducing agents known. Vanadous oxide is also a black powder and its salts are green in solution. Hypovanadic oxide forms blue solutions of vanadyl salts. Vanadium pent oxide is a yellowish red powder which is sparingly soluble in water. The basic properties of vanadium oxides diminish as the oxygen part of the molecule increases and the higher oxides exhibit acidic as well as basic properties.