lanthanoid contraction is caused due to - [AIEEE-2006]a)The same effec...
The Lanthanide Contraction is caused by a poor shielding effect of the 4f electrons. Gd because as atomic number increases, the atomic radius decreases. These electrons are do not shield good, causing a greater nuclear charge.
View all questions of this test
lanthanoid contraction is caused due to - [AIEEE-2006]a)The same effec...
Understanding Lanthanoid Contraction
Lanthanoid contraction refers to the gradual decrease in the ionic radii of the lanthanide series elements from lanthanum (La) to lutetium (Lu). This phenomenon is primarily due to the behavior of the 4f electrons.
Key Factors Contributing to Lanthanoid Contraction
- Effective Nuclear Charge
- As we move from La to Lu, the number of protons in the nucleus increases, leading to a higher effective nuclear charge.
- Imperfect Shielding by 4f Electrons
- The 4f electrons are not very effective in shielding the outer electrons from the nucleus.
- Due to their poor shielding ability, the outer electrons feel a stronger nuclear charge, resulting in a greater attraction towards the nucleus.
- Decreased Ionic Radii
- As the attraction increases, the size of the ions decreases. This effect becomes more pronounced with each subsequent element in the series.
- Consequences of Lanthanoid Contraction
- This contraction leads to similarities in the chemical properties of the lanthanides and can affect the physical properties, such as melting and boiling points.
Conclusion
The correct explanation for lanthanoid contraction is option 'B': the imperfect shielding on outer electrons by 4f electrons from the nuclear charge. This key factor results in a consistent decrease in ionic radii across the lanthanide series, despite the increasing atomic number. Understanding this concept is crucial for grasping the behavior of lanthanides in various chemical contexts.
To make sure you are not studying endlessly, EduRev has designed Class 11 study material, with Structured Courses, Videos, & Test Series. Plus get personalized analysis, doubt solving and improvement plans to achieve a great score in Class 11.