Lanthanoid ions with 4f7 configuration are : Choose the correct answer from the options given below :
- B and E only
- B and C only
- A and D only
- A and B only
Answer
(4) A and B only
Solution
Number of 4f electrons = Z - 54 - charge (the 6s, 5d electrons go first)
A. Eu2+: 63-54-2 = 7; B. Gd3+: 64-54-3 = 7
C. Eu3+: 6; D. Tb3+: 8; E. Sm2+: 6
A and B
Answer: (4)