Which of the following statement is true?a)Actinoid contraction is sma...
Actinoid Contraction and Lanthanoid Contraction
Actinoid contraction and lanthanoid contraction are terms used to describe the decrease in atomic and ionic radii of the elements in the actinide and lanthanide series, respectively.
Actinoid Contraction
- Actinoid contraction refers to the decrease in atomic and ionic radii of the elements in the actinide series.
- It is caused by the imperfect shielding of the 5f electrons by the 6s and 6p electrons.
- The 5f electrons are located closer to the nucleus and experience a greater effective nuclear charge, which leads to a smaller atomic and ionic radius.
- Actinoid contraction is observed in the actinide series from thorium (Z=90) to lawrencium (Z=103).
Lanthanoid Contraction
- Lanthanoid contraction refers to the decrease in atomic and ionic radii of the elements in the lanthanide series.
- It is caused by the imperfect shielding of the 4f electrons by the 5s, 5p, and 6s electrons.
- The 4f electrons are located closer to the nucleus and experience a greater effective nuclear charge, which leads to a smaller atomic and ionic radius.
- Lanthanoid contraction is observed in the lanthanide series from cerium (Z=58) to lutetium (Z=71).
Comparison of Actinoid Contraction and Lanthanoid Contraction
- Actinoid contraction is greater than lanthanoid contraction.
- The 5f electrons in the actinide series experience a greater effective nuclear charge than the 4f electrons in the lanthanide series, which leads to a greater decrease in atomic and ionic radii.
- Actinoid contraction is also observed over a smaller range of elements than lanthanoid contraction.
Which of the following statement is true?a)Actinoid contraction is sma...
Because 5f electrons have poor shielding effect as compared to 4f electrons. therefore, the effect of increased nuclear charge leading to contraction in size, is more in case of actinoids.