Reason of lanthanoid contraction is - Vidyadip

MCQ

Reason of lanthanoid contraction is

✓
negligible screening effect of $'f'-$orbitals
B
increasing nuclear charge
C
decreasing nuclear charge
D
decreasing screening effect.

✓

Answer

Correct option: A.

negligible screening effect of $'f'-$orbitals

a
Lanthanoid contraction is the regular decrease in atomic and ionic radii of lanthanides. This is due to the imperfect shielding [or poor screening effect ] of $l-$orbitals due to their diffused shape which unable to counterbalance the effect to the increased nuclear charge. Hence, the net result is a contraction in size of lanthanoids.

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