Question

The reason for the stability of $Gd^{3+}$ ion is

• A. 4f subshell-half filled
• B. 4f subshell-completely filled
• C. Possesses the general electronic configuration of noble gases
• D. 4f subshell empty

Answer 1

Answer: (A)

4f subshell-half filled

Answer 2

Gd (Z = 64) : $[Xe]^{54}\, 4f^7 \,5d^1 \, 6s^2$ $Gd^{3+} : [Xe]^{54} \, 4f^7$ $Gd^{3+}$ is stable due to the presence of exactly half filled $4f$-subshell.