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Explain the lanthanoid contraction |
Answer» SOLUTION :In lanthanoid series, there is overall decreases in the atomic and ionic radii cumulatively. This is called lanthanoid contraction and it is the unique feature in the chemistry of lanthanoid  When moved from cerium to lutetium, there is increases in the nuclear charge with the increase in atomic number and the electrons are added in 4f orbital successively at the same time. The sheilding of one 4f-electron by ANOTHER is very poor than d-electrons. As a RESULT, the nuclear charge experienced by 4f-electrons increases which causes reduction in SIZE to an atom or ion. The nuclear charge steadily increase with the atomic number on 4f-electrons and there is constant DECREASE of size of atom/ion because of poor sheilding of 4f-electrons. This is known as lanthanoid contraction. The decrease in size is more sharp in case of tripositive ions than in atoms |
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