d and f BLOCK ELEMENTS

Why are ns electrons lost before (n-1)d electrons when d-block elements form ions?

• The ns orbitals are lower in energy than the (n-1)d orbitals
• The ns orbitals are higher in energy than the (n-1)d orbitals in the ground state of transition metal atoms
• The ns electrons are closer to the nucleus
• The (n-1)d electrons are more stable

Which configuration of an ion formed by a 3d transition element is considered particularly stable and can influence ionisation enthalpy trends?

• d0 configuration
• d5 configuration
• d10 configuration
• s2 configuration

What happens to the relative energies of 4s and 3d orbitals when an electron is removed from a 3d transition element?

• The 4s orbital always becomes lower in energy
• The 3d orbital always becomes lower in energy
• The removal of an electron can alter the relative energies of 4s and 3d orbitals
• The energy difference between them remains constant

Why is the increase in successive ionisation enthalpies (second, third, etc.) not as steep for transition elements as for non-transition elements?

• The d-orbitals are higher in energy
• One d-electron does not shield another d-electron effectively from the nuclear charge
• The nuclear charge decreases with each ionisation
• The atomic radius increases significantly

What is the main reason for the variation in ionisation enthalpy along a transition series being much less than that along a period of non-transition elements?

• The transition elements have fewer electrons
• The increased nuclear charge is effectively shielded by the filling of inner d orbitals
• The transition elements have lower atomic masses
• The transition elements form only cations