d and f BLOCK ELEMENTS

What is the most frequently observed and stable oxidation state for actinoids overall?

• +2
• +3
• +4
• +5

What is the primary reason for the extensive range of oxidation states observed in actinoids?

• High atomic masses of actinoids
• Strong metallic bonding characteristics
• The energy levels of 5f, 6d, and 7s orbitals are relatively close to each other
• Complete filling of the 5f orbitals

What is the main reason the actinoid contraction is more pronounced than the lanthanoid contraction?

• Actinoids have larger atomic numbers
• Actinoids have better nuclear charge screening
• The 5f electrons provide less effective shielding of outer electrons from the increasing nuclear charge
• Actinoids have smaller initial ionic radii

What contraction phenomenon is observed in the actinoid series, similar to the lanthanoid series?

• Actinoid expansion
• Lanthanoid expansion
• Actinoid contraction
• Poor nuclear shielding effect

Why do 5f electrons in actinoids participate more in chemical bonding than 4f electrons in lanthanoids?

• 5f orbitals are completely filled
• 5f electrons are always lost first in reactions
• 5f orbitals are less effectively shielded and more spatially accessible than 4f orbitals
• 5f electrons have inherently lower energy levels