Topic: Lanthanoids and lanthanoid contraction· d- and f-Block Elements

Zr (Z=40) and Hf (Z=72) have similar atomic and ionic radii because of :

1. belonging to same group

2. diagonal relationship

3. lanthanoid contraction

4. having similar chemical properties

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Answer: 3. lanthanoid contraction

Key idea: lanthanoid contraction.

Between Zr (4d) and Hf (5d) come the 14 lanthanoids, whose poor shielding 4f electrons cause a steady decrease in size. This cancels the normal increase in size from 4d to 5d, so Zr and Hf have almost the same radii.

Doubtly AI · 30 Oct 2026 AI-generated · not yet verified Report

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Zr (Z=40) and Hf (Z=72) have similar atomic and ionic radii because of :

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