Titanium subgroup

These three elements have a complicated chemistry. They are much less abundant than the titanium subgroup. 

Zirconium [7440-67-7] is classified ia subgroup IVB of the periodic table with its sister metallic elements titanium and hafnium. Zirconium forms a very stable oxide. The principal valence state of zirconium is +4, its only stable valence in aqueous solutions. The naturally occurring isotopes are given in Table 1. Zirconium compounds commonly exhibit coordinations of 6, 7, and 8. The aqueous chemistry of zirconium is characterized by the high degree of hydrolysis, the formation of polymeric species, and the multitude of complex ions that can be formed. 

Ammino-derivatives op Subgroup A—Derivatives of Titanium Kilts, Zirconium Salts, Cerium, and Thorium Halides. 

Leis, J., Perkson, A., Arulepp, M., Nigu, P., and Svensson, G. Catalytic effect of metals of the iron subgroup on the chlorination of titanium carbide to form nanostructural carbon. Carbon 40, 2002 1559-1564. 

In a further extension of its interest to develop a range of standard catalysts, EUROCAT authorized a subgroup of its members to select a zeolite and to initiate a programme of work on its use [9i, 31]. The subgroup, under the leadership of Professor Jacobs, KU Leuven, chose titanium silicalite-1 (TS-1) in this zeolite, some... 

The cited reference discusses the further detailed and necessary separations within each of the specified subgroups titanium (1.1), alkaline earth (1.3), metal amine (1.4), sulfide (2.1), aluminum (2.4), chromium (2.5), lead (2.6), arsenic (2.7), halogen (3.3), phosphorus (3.5), sulfur and fluorine (3.6). 

Zirconium (Zr, CAS 7440-67-7, atomic number 40, atomic mass 91.22) has a melting point of 1852 °C and a boiling point of 4377 °C. It is a hard, lustrous, silvery metal, in contrast to fine zirconium powder, which is black. Zirconium belongs to Subgroup IV of the Periodic Table of the elements, between the elements titanium and hafnium - two metals with which it is often found in nature. Zirconium has oxidation states ranging from II to IV, of which the tetravalent is relatively stable and abundant (Venugopal and Luckey 1979). Zirconium is very corrosion-resistant and is unaffected by alkalis or acids (except for HF). 

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