The early actinoids display a vastly wider, erratic range of oxidation states compared to the lantha — d and f Block Elements Chemistry Question

💡 Solution & Explanation

In lanthanoids, the $4f$ electrons are deeply buried and tightly held. Conversely, in the early actinoids, the $5f, 6d$, and $7s$ energy levels possess highly comparable, nearly indistinguishable energies. This minuscule gap allows electrons from all three subshells to readily participate in covalent bonding.