Based on the periodic table, what is the absolute atomic number () of the extremely stable Lanthanid — d and f Block Elements Chemistry Question

💡 Solution & Explanation

Lutetium ($Lu$) sits at the very end of the lanthanide series with an atomic number of $71$. Its neutral ground state configuration is $[Xe] 4f^{14} 5d^1 6s^2$. When it forms its stable $+3$ ion ($Lu^{3+}$), it loses the $5d$ and $6s$ electrons entirely, leaving a perfectly closed, completely filled $[Xe] 4f^{14}$ subshell.