Verified Solution • 2025–26 Session moderate

QJEEM06Chf5a3: JEE Main 2006 Chemistry - Class 12 JEEM06Chf5a3 Solution: Lanthanoid contraction is caused due to :

Lanthanoid contraction is caused due to :

Multiple Choice Options

  • A the appreciable shielding on outer electrons by 4f electrons from the nuclear charge
  • B the appreciable shielding on outer electrons by 5d electrons from the nuclear charge
  • C the same effective nuclear charge from Ce to Lu
  • D the imperfect shielding on outer electrons by 4f electrons from the nuclear charge

Step-by-Step Verified Solution

The main reason of lanthanide contraction is, poor shielding of 4f electrons on the outer most shell electrons. As f orbital is defused nature so shielding of 4f electron is imperfect that is why nucleus can attract outer most shell electron easily and the size of atom decreases.

In lanthanides, there is poorer shielding of 5d electrons by 4f electrons resulting in greater attraction of the nucleus over 5d electrons and reduction of the atomic radii.

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