The Lanthanoid contraction is responsible for | vedclass

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(C) The elements following the lanthanoids in the periodic table are influenced by the lanthanoid contraction. For example,the atomic radius of the me

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$Zr$ and $Hf$ have about the same radius

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(C) The elements following the lanthanoids in the periodic table are influenced by the lanthanoid contraction. For example,the atomic radius of the metal zirconium,$Zr$,(a period-$5$ transition element) is $159 \ pm$ and that of hafnium,$Hf$,(the corresponding period-$6$ element) is $156 \ pm$. The radii are very similar even though the number of electrons increases from $40$ to $72$ and the atomic mass increases from $91.22$ to $178.49 \ g/mol$. The increase in mass and the nearly unchanged radii lead to a steep increase in density from $6.51$ to $13.35 \ g/cm^3$. Zirconium and hafnium,therefore,have very similar chemical behaviour,having closely similar radii and electron configurations. Radius-dependent properties such as lattice energies,solvation energies,and stability constants of complexes are also similar.

The Lanthanoid contraction is responsible for the fact that

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