JEE MAIN - Chemistry (2005 - No. 42)
Which of the following factors may be regarded as the main cause of lanthanide
contraction?
Poor shielding of one of 4f electron by another in the subshell
Effective shielding of one of 4f electrons by another in the subshell
Poorer shielding of 5d electrons by 4f electrons
Greater shielding of 5d electrons by 4f electrons
Penjelasan
The main reason of lanthanide contraction is, poor shielding of 4f electrons on the outer most shell electrons.
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.
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.