What is the general outer electronic configuration assigned to the Lanthanoid series? — d and f Block Elements Chemistry Question

💡 Solution & Explanation

The formally accepted configuration for the Lanthanoids (4f series) is $[Xe] 4f^{1-14} 5d^{0-1} 6s^2$. The $4f$ and $5d$ subshells are very close in energy, leading to occasional $5d^1$ occupancy (like in Gadolinium).