The irregular trend in the first ionization enthalpy is attributed to the alteration of relative energies between 4s and 3d orbitals upon the removal of one electron, affecting the shielding of 4s electrons by the increasing nuclear charge along the ...

The variation in ionization enthalpy along a series of transition elements is less pronounced than in a period of non-transition elements. While the first ionization enthalpy generally increases, the increase in the second and third ionization enthalpies is significantly higher ...

The lanthanoid contraction results in a decrease in metallic radius and an increase in atomic mass, contributing to a general increase in the density of elements in the transition series from titanium (Z = 22) to copper (Z = 29).

The lanthanoid contraction is caused by imperfect shielding of one 4f electron by another, similar to the shielding observed in an ordinary transition series. However, the shielding effectiveness of 4f electrons is less than that of d electrons, leading to ...

NCERT Solutions for Class 12 Chemistry Chapter 3 Chemical Kinetics Page No. 22 NCERT Academic Session 2023-2024.