d and f BLOCK ELEMENTS

Why do actinoids generally show a wider range of oxidation states compared to lanthanoids?

• They have more electrons
• They are more electronegative
• The 5f orbitals are less buried and more accessible for bonding than the 4f orbitals
• They have a larger atomic radius

What is the primary oxidation state exhibited by actinoids?

• +1
• +2
• +3
• +4

What is the main reason for the relatively high melting points of lanthanoid metals?

• Covalent bonding between atoms
• Ionic bonding
• Metallic bonding involving the delocalization of the outer 6s electrons
• Hydrogen bonding

What is the typical coordination number for Ln³⁺ ions in their complexes?

• 4 or 6
• 6 or 7
• 8 or 9
• 10 or 12

Why do lanthanoid ions generally not form stable complexes with common ligands like H₂O or NH₃ compared to transition metal ions?

• They do not form any complexes
• They have a full outer shell
• The 4f orbitals are contracted and buried, leading to less effective orbital overlap with ligands
• They prefer to exist as free ions