d and f BLOCK ELEMENTS

What is the primary reason for the lanthanoid contraction?

• Increase in nuclear charge
• Imperfect shielding of 4f electrons
• Increase in atomic mass
• Perfect shielding of 4f electrons

What is the role of the 4f orbitals in determining the properties of 5d series elements?

• They provide excellent shielding for 5d electrons
• Their poor shielding causes Lanthanoid contraction, affecting 5d element sizes
• They determine the number of valence electrons in 5d elements
• They have no effect on 5d element properties

Why is the term 'noble character in reactions' used for metals with high enthalpies of atomisation?

• Because they are gases
• Because they are highly coloured
• Because the high energy barrier for atomisation makes them less reactive
• Because they have low density

How does the concept of effective nuclear charge help explain the trends in transition metal radii?

• It decreases across a series due to effective d shielding
• It remains constant across a series
• It increases across a series due to poor d shielding, pulling electrons closer
• It fluctuates randomly across a series

What is the consequence of the poor shielding effect of f electrons across the lanthanide series?

• Regular increase in atomic radii
• No change in atomic radii
• Regular decrease in atomic radii (Lanthanoid contraction)
• Random fluctuation in atomic radii