Question

Lanthanoid contraction is due to

• A. the same effective nuclear charge
• B. partially filling of f and d-orbitals
• C. the imperfect shielding on outer electrons by 4f-electrons from the nuclear charge
• D. the perfect shielding on outer electrons by 4f-electrons from the nuclear charge

Answer 1

Answer: (C)

Lanthanoid contraction is due to poor shielding of electrons of 4f-orbital. It is even less than the shielding shown by d-electron.