Moving from Copper () to Zinc () at the very end of the 3d series, the atomic radius slightly increa — d and f Block Elements Chemistry Question

💡 Solution & Explanation

At the end of the series, the $3d$ orbitals become completely filled ($d^{10}$). The extreme crowding and electron-electron repulsion within this penultimate shell overwhelm the effective nuclear charge, causing the valence shell to expand.