d and f BLOCK ELEMENTS

What is the primary reason for the formation of interstitial compounds by transition metals?

• Large atomic radii of transition metals
• Weak metallic bonding
• Small atoms can fit into the holes in the close-packed metal lattice
• High reactivity with halogens

Why is the +3 oxidation state the most common for lanthanoids?

• It is the only stable oxidation state
• It results from losing all 4f electrons
• It corresponds to the stable electronic configuration after losing 6s and one 5d or 4f electron
• It is required for forming binary compounds

What is the main industrial application of the Ziegler-Natta catalyst system involving TiCl4 and Al(CH3)3?

• Oxidation of alcohols
• Hydrogenation of alkenes
• Polymerization of ethylene to polythene
• Dehydration of alcohols

In the preparation of potassium dichromate, what is the purpose of fusing chromite ore with alkali in the presence of air?

• To reduce chromium to elemental form
• To remove iron as a pure metal
• To oxidize chromium from +3 to +6 oxidation state
• To form a simple salt without changing oxidation states

What structural feature allows transition metals to readily form complex ions?

• Large ionic radii
• High electronegativity
• Availability of partially filled or empty d orbitals to accept electron pairs
• Low ionization energies