The d-And-f-Block Elements

Short Answer Type

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Actinoid contraction is greater from element to element than lanthanoid contraction. Why?

In actinoids, 5f orbitals are filled. These 5forbitals have a poorer shielding effect than 4f orbitals (in lanthanoids). Thus, the effective nuclear charge experienced by electrons in valence shells in case of actinoids is much more that that experienced by lanthanoids. Hence, the size contaction in actinoids is greater as compared to that in lanthanoids.
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