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InterviewSolution
| 1. |
What is Lanthanoid contraction ? Explain , why lanthanum `(Z=57)` forms `La^(3+)` ion, while cerium `(Z=58)` forms `Ce^(4+)` ion ? |
| Answer» La has the electronic configuration of [Xe] `4f^(0) 5f^(1), 6s^(2)` after losing 3 electrons La forms `La^(3+)` ion which is stable due to empty 4f orbitals while Ce has the electronic configuratin of [Xe] `4f^(2),5d^(0) 6s^(2)` after losing 4 electrons Ce forms `Ce^(4+)` ion which is stable due to empty 4f orbitals. Thus, Lanthanum forms `La^(3+)` ion while cerium forms `Ce^(4+)` ions. | |