Question

What is lanthanoid contraction & what ar the consequences of lanthanoid contraction?

Answer 1

The steady decrease in the ionic radii of M³+ cation in the lanthanide series is called Lanthanide contraction.

It is due to the imperfect shielding of 4f electron by another in same subshell.

CONSEQUENCES

*Decrease in ionic radii.
*Decrease in their tendency to act  as reducing agent.

Answer 2

Hey !!

In lanthanoids, with increasing atomic number, the atomic and ionic radii decreases from one element to the other, but the decrease is very small. It is because, for every additional proton in the nucleus, the corresponding electron goes into a 4f-subshell, which is too diffused to screen the nucleus as effectively as the more localised inner shell. Hence, the attraction of the nucleus for the outermost electrons increases steadily with the atomic increases.

The consequences of lanthanoid contraction are as follows:-

1. The properties of second and third transition series are similar.

2. Basic strength decreases from La(OH)₃ to Lu(OH)₃.

3. Lanthanide contraction makes separation of lanthanoids possible.

Hope it helps you !!