Question

The extent of actionionid contraction is greater than lanthanoid contraction. Explain.

Answer 1

Hint: you have to know the properties of lanthanide and action for example: (filling of 4f orbitals takes place in lanthanoids and in actinoids filling of 5f orbitals takes place) to explain the statement mentioned in the question.

Complete answer:
Filling of 4f orbitals takes place in lanthanides while filling of 5f orbitals occurs in actinoids. Actinoid contraction (Decrease) is greater in terms of lanthanides since 5f electrons have poor shielding in comparison to 4f electrons. Due to the weak shielding effect of 5f, an aspect of an actinide series may receive an increased nuclear charge. Note the 4f shielding effect is greater than 5f. The shielding effect/screening effect is inversely proportional to the nuclear charge, which means greater the nuclear charge lesser the shielding effect gets, a contraction will occur. Therefore, the contraction of actinoids is stronger than that of lanthanoids.

Note: In a multi-electron atom, the valence shell's electrons are attracted to the nucleus, and these electrons are therefore repelled by the electrons found inside the shells. Despite this, the actual attraction force between the nucleus and the valence electrons is slightly diminished by the repulsive forces acting in opposite directions due to the existence of electrons in the inner shells, this reduction in the attraction force imposed by the nucleus on the valence electrons is called the screening effect or the shielding effect screening magnitude depending on the number of the internal electrons the higher the internal electrons are the higher the screening effects get.
The constant of the screening effect is represented by the symbol$\sigma $.