d and f BLOCK ELEMENTS

What is the primary reason for the relatively low variation in atomic radii across the 3d transition series?

• The electrons are added to the same shell
• Effective shielding of outer electrons by the increasing number of inner 3d electrons
• The nuclear charge remains constant
• The electrons occupy higher energy levels

Why do transition elements have high enthalpies of atomisation?

• Due to weak van der Waals forces
• Due to strong metallic bonding involving delocalised d-electrons
• Due to high ionisation energies
• Due to low atomic masses

What is the typical electronic configuration of a M2+ ion formed from a first-row transition metal?

• (n-1)d^(n-2) ns^2
• (n-1)d^n ns^2
• (n-1)d^n
• ns^2

Which factor primarily contributes to the irregular trend in the first ionisation enthalpy of 3d series transition metals?

• The completely filled 3d subshell in zinc
• Changes in the relative energies of 4s and 3d orbitals upon electron removal
• The presence of unpaired electrons
• The decrease in atomic radius across the series

How does the presence of unpaired d-electrons primarily affect the physical properties of transition elements?

• It makes them more reactive with water
• It leads to stronger interatomic bonding and higher enthalpies of atomisation
• It causes them to be highly volatile
• It results in lower electrical conductivity