In the group 4 transition metals, it is observed that the ratio of atomic radii r( Zr ) r( Ti ) is significantly greater than 1, whereas the ratio r( Hf ) r( Zr ) is approximately 1. What is the primary reason for the ratio r( Hf ) r( Zr )

Question

In the group 4 transition metals, it is observed that the ratio of atomic radii r( Zr ) r( Ti ) is significantly greater than 1, whereas the ratio r( Hf ) r( Zr ) is approximately 1. What is the primary reason for the ratio r( Hf ) r( Zr ) being approximately 1?

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Correct answer: A. The poor shielding effect of the completely filled 4f orbitals in Hafnium

The atomic radius of Hafnium (Hf) is almost identical to that of Zirconium (Zr) due to the lanthanoid contraction. Before the 5d series begins, the 4f orbitals are completely filled with 14 electrons. The 4f electrons shield the increasing nuclear charge very poorly. This poor shielding causes a significant contraction in the size of the valence shell, which essentially cancels out the expected increase in size down the group from the 4d to the 5d series. Hafnium does not contain 5f electrons, and the inert pair ef

In the group 4 transition metals, it is observed that the ratio of atomic radii r( Zr ) r( Ti ) is significantly greater than 1, whereas the ratio r( Hf ) r( Zr ) is approximately 1. What is the primary reason for the ratio r( Hf ) r( Zr ) being approximately 1?

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