The 4th group metals remarks about their general chemical properties and reactivity

3 The 4th group metals remarks about their general chemical properties and reactivity 

The three metals are chemically similar. The especially close similarity between the Zr and Hf chemistries can be remarked. This may be mainly related to the effect of the lanthanide contraction having made their radii (both atomic and ionic) nearly identical. In comparison with Ti, the larger atomic dimensions of Zr and Hf result in more basic oxides and tendency to achieve higher coordination numbers, etc. 

Element 1 st ionization energy/kJ/mol 2nd ionization energy /kJ/mol 3rd ionization energy /kJ/mol 4th ionization energy /kJ/mol 5th ionization energy/kJ/mol 

Element (allotrope) Temperature range/°C Pressure/GPa Crystal structure Lattice parameters/ pm Atomic volume/ pm3106 Molar volume/ cm3/mol Density/ g/cm3 

Several organo-titanium compounds with the oxidation states IV, III, II, 0,-1 have been prepared. A starting point was the discovery by Ziegler et al. (1955), Ziegler (1963) and Natta et al. (1955) and Natta (1963) of the catalytic properties of TiClj-Al-alkyl mixtures in hydrocarbons in reactions such as the ethylene and propylene polymerization. 

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