d and f BLOCK ELEMENTS

What is the main cause of the Lanthanoid contraction?

• Poor shielding by 4f electrons
• Filling of 4f orbitals before 5d orbitals
• Increased nuclear charge in lanthanides
• High ionisation energies of lanthanides

Why do the atomic radii of the third (5d) series become virtually the same as those of the corresponding members of the second (4d) series?

• Poor shielding by 4d electrons
• Lanthanoid contraction compensates for the expected increase
• Poor shielding by 5d electrons
• Increased nuclear charge in 5d elements

How does the ionic radius generally change for ions of the same charge within a given transition metal series as the atomic number increases?

• Progressive increase
• Remains constant
• Progressive decrease
• Random variation

What property is generally associated with metals having very high enthalpies of atomisation?

• High reactivity
• Low boiling points
• Noble character in reactions
• High electrical conductivity

Which series of transition metals generally exhibits the highest enthalpies of atomisation?

• First series
• Second and third series
• Only the first series
• All series equally