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Questions
What is lanthanoid contraction?
What do you understand by lanthanoid contraction?
What is lanthanoid contraction? Explain.
What is meant by lanthanide contraction?
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Solution 1
The lanthanide series of elements is defined as a gradual reduction in atom size, known as lanthanoid contraction. This reduction occurs due to insufficient shielding of additional electrons in the 4f subshell by filled 5s and 5p orbitals. As a result, the effective nuclear charge increases, resulting in smaller atomic sizes.
Solution 2
- The size of the atoms and ions has been found to routinely decrease as one moves from cerium to lutetium. In the case of tripositive ions, this size reduction is more consistent.
- The nuclear charge rises with atomic number when one transitions from Ce to Lu, and the inner 4f-orbital gains the differentiating electron.
- The shielding of one 4f-electron by another from growing nuclear charge is imperfect due to the irregular geometries of 4f-orbitals.
- As a result, each 4f-electron experiences an increasing effective nuclear charge as the atomic number rises. As each electron in the 4f-subshell is added, the size is somewhat decreased.
- As a result, the size steadily contracts as the effective nuclear charge steadily rises with each additional electron in the 4f-subshell.
- Lanthanoid contraction refers to the cumulative effect of successive contractions on all lanthanoids.
- The total contraction in atomic radius in going from Ce to Lu is about 15 pm.
- Atomic radii show a tendency to decrease in size; however, the pattern is irregular.
Notes
Students can refer to the provided solutions based on their preferred marks.
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