Name: Lanthanoid Contraction
Uploaded: 2019-07-19
Duration: 4 min 23 s
Description: The steady decrease in atomic and ionic sizes of lanthanide elements with increasing atomic number is called lanthanoid contraction. It affects certain prope...

Question

What is lanthanide contraction? Write any two of its consequences.

Accepted Answer

The atomic radii of lanthanoids decrease with the increase in their atomic number. But this decrease is very small. The atomic or ionic radii of lanthanoids decrease in a period from left to right because their last electron enters subshell which has a poor shielding effect, therefore, the effective nuclear attraction on outer electrons increases and the size of the lanthanoids decreases. This phenomenon is called lanthanoid contraction.

The consequences of lanthanoid contractions are the following;

(I) The basicity of the trihydroxides of lanthanide elements decreases with the increase in their atomic number.

(II) The sizes of the elements of the third transition series are approximately similar to the atomic sizes of the second transition series.

What is lanthanide contraction? Write any two of its consequences.

Important Questions on The f-block Elements

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