Gadolinium belongs to 4f - series. It's atomic number is 64. Which of the following is the correct electronic configuration of gadolinium -

Options

A. `[Xe]4f^(7)5d^(1)6s^(2)`
B. `[Xe]4f^(6)5d^(2)6s^(2)`
C. `[Xe]4f^(8)6d^(2)`
D. `[Xe]4f^(9)5s^(1)`

Answer

A

Explanation

Elements of 4f - series have configuration `4f^(1-14)5d^(0-1)6s^(2)`. So gadolinium has the configuration : `[Xe]4f^(7)5d^(1)6s^(2)`. (extra stability of half - filled f - subshell)