Question

1. What is lanthanide Constnaction? How would you
for it? What are it important Consequences?
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Answer 1

The Lanthanide Contraction is caused by a poor shielding effect of the 4f electrons. Gd because as atomic number increases, the atomic radius decreases. Yb because it has a larger atomic number. Because the elements in Row 3 have 4f electrons.

Answer 2

In case of lanthanide elements , it has been experimentally found that with increasing atomic number , the atomic and ionic size of lanthanide elements gradually decreases from lanthanum to lutetium.

It is very much regular for lanthanide ions ( Ln 3+) . It will be seen that on going from La 3+ to Lu 3+, the ionic radius shrinks from 115 pm to 93 pm .

The steady decrease in ionic radius all along the series amounting in all to 22 pm , is called lanthanide contraction .