d and f BLOCK ELEMENTS

How does the actinoid contraction manifest as one moves across the actinoid series?

• It causes a steady increase in atomic or ionic radii
• It causes random and unpredictable fluctuations
• It results in a steady decrease in atomic or ionic radii
• It has no significant effect on radii

Which oxidation state is NOT listed for Uranium (U) in the representation of Table 4.11?

• +3
• +4
• +6
• +7

What is a key difference in the chemical behavior of 5f electrons in actinoids compared to 4f electrons in lanthanoids?

• 5f electrons are inherently more stable
• 5f electrons are always paired in their orbitals
• 5f electrons are less buried and participate more significantly in bonding processes
• 5f electrons occupy lower energy levels than 4f electrons

For which actinoid does the formal filling of the 5f subshell commence according to the text?

• Actinium (Ac)
• Thorium (Th)
• Protactinium (Pa)
• Uranium (U)

What is the electronic configuration given for Curium (Cm) in the text?

• [Rn] 5f⁶ 7s²
• [Rn] 5f⁸ 7s²
• [Rn] 5f⁷ 7s²
• [Rn] 5f⁷ 6d¹ 7s²