d and f BLOCK ELEMENTS

What is the primary reason for the softness of lanthanoid metals compared to many transition metals?

• Large atomic radii
• High density
• Weaker metallic bonding due to localized 4f electrons
• Low melting points

Why are the +2 and +4 oxidation states sometimes observed in lanthanoids despite +3 being principal?

• They are more stable than +3
• They result from losing all 4f electrons
• Energy levels allow removal of different numbers of electrons under certain conditions
• They are required for biological function

What is the main consequence of the similar ionization enthalpies in transition elements?

• Formation of only ionic compounds
• Low reactivity
• Ability to exhibit multiple stable oxidation states
• Formation of only covalent compounds

Which property of transition metals is most closely related to their use in electrical wiring?

• High melting point
• Malleability
• High electrical conductivity due to delocalized electrons
• Paramagnetic properties

What is the main reason transition elements readily form complexes with ligands like H2O, NH3, and CN-?

• High positive charge on the metal ions
• Large ionic radii
• Availability of vacant or partially filled d orbitals to accept electron pairs
• Low electronegativity