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प्रश्न
Account for the following :
Zr and Hf have almost similar atomic radii.
उत्तर
Due to lanthanide contraction, Zr and Hf have almost similar atomic radii. It can be explained on the basis of shielding effect. The electrons present in inner shells, shield the outer electrons from nuclear charge, making them experience a low effective nuclear charge. The shielding effect exerted by the electrons decreases in the order s > p > d > f. The f subshell poorly shields the outer electrons from nuclear attraction, which results in more attractive pull of nucleus on outer electron. In case of post lanthanide elements like Hf, 4f subshell is filled and it is not very effective at shielding the outer shell electrons. Therefore, Zr and Hf have almost similar atomic radii.
संबंधित प्रश्न
Compare the chemistry of actinoids with that of the lanthanoids with special reference to atomic and ionic sizes.
Explain effects of lanthanoid contraction
What are the consequences of lanthanoid contraction?
Explain the cause of lanthanoid contraction?
What is Lanthanoid contraction?
Explain the cause of Lanthanoids contraction.
Name an element of lanthanoid series which is well knwon to shown +4 oxidation state. Is it a strong oxidising agent or reducing agent?
Which of the following lanthanoids show +2 oxidation state besides the characteristic oxidation state +3 of lanthanoids?
(i) \[\ce{Ce}\]
(ii) \[\ce{Eu}\]
(iii) \[\ce{Yb}\]
(iv) \[\ce{Ho}\]
Although Zr belongs to 4d and Hf belongs to 5d transition series but it is quite difficult to separate them. Why?
Assertion: There is a continuous increase in size among Lanthanoids with an increase in atomic number.
Reason: Lanthanoids do not show Lanthanoid contraction.
