Gadolinium (, ) possesses an anomalous ground state electronic configuration. What is the total numb — Periodic Table and Periodicity Chemistry Question

💡 Solution & Explanation

Gadolinium ($Z=64$) belongs to the Lanthanide series. Instead of the expected $[Xe] 4f^8 6s^2$, one electron occupies the 5d orbital to maintain a highly stable half-filled 4f subshell. Its true configuration is $[Xe] 4f^7 5d^1 6s^2$. The 4f subshell provides 7 unpaired electrons, and the 5d subshell provides 1 unpaired electron, yielding a total of $7 + 1 = 8$ unpaired electrons.