Regarding the highly complex, radioactive series of Actinoids ( -block), which of the following stat — d and f Block Elements Chemistry Question

💡 Solution & Explanation

(A) is correct; every single Actinoid element is radioactive. (B) is correct; unlike Lanthanoids (mostly $+3$), Actinoids can show up to $+7$ (e.g., $Np$, $Pu$) because their $5f, 6d, 7s$ energy levels are very close, allowing all to participate in bonding. (C) is correct; $5f$ electrons shield much worse than $4f$ electrons, making Actinide contraction greater. (D) is incorrect; Actinoids actually have a *greater* tendency to form complexes than Lanthanoids due to their higher charge densities and highly available, extended $5f$ orbitals.