PUC Karnataka Science Class 12Department of Pre-University Education, Karnataka
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Solution for Define Lanthanoid Contraction. - PUC Karnataka Science Class 12 - Chemistry


Define lanthanoid contraction.

What is lanthanoid contraction?

Solution 1

Lanthanoid contraction:-

With an increasing atomic number in the lanthanoid series, there is a progressive decrease in the atomic as well as ionic radii of trivalent ions from La3+ to Lu3+.

This regular decrease (contraction) in the size of the atoms and ions with increasing atomic number is known as lanthanoid contraction.

Solution 2

Lanthanoid Contraction : In the lanthanoids , the electrons are getting filled in the 4f-subshell. On moving from left to right, the nuclear charge increases and this increase is expected to be compensated by the increase in the magnitude of shielding effect by the 4 f- electrons However,
the f-electrons have very poor shielding effect. Consequently, the atomic and ionic radii decrease from left to right and this is knwon as lanthanoid contraction.

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 NCERT Chemistry Textbook for Class 12 Part 1 (with solutions)
Chapter 8: The d-block and f-block Elements
Q: 7 | Page no. 234
Solution for question: Define Lanthanoid Contraction. concept: F-block Elements - The Lanthanoids. For the courses PUC Karnataka Science, CBSE (Science), HSC Science (Electronics), HSC Science (Computer Science), HSC Science (General)