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Actinoid contraction is greater from ele...

Actinoid contraction is greater from element to element than lanthanoid contraction. Why?

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The decrease in atomic radli in actinoid elements is greater than lanthanoid contraction because 5felectrons 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 actinoid elements.
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Reason of lanthanoid contraction is

What is meant by 'lanthanoid contraction'?

The gradual decrease in size (actionoid contraction) is from element to element is greater among the actinoids than that among the lanthanoids (lanthanoid contraction).

Assign reasons for the following : (i) The enthalpies of atomisation of transition elements are high. (ii) The transition metals and many of their compounds act as good catalyst. (iii) From element to element the actinoid contraction is greater than the lanthanoid contraction. (iv) The E^(@) value for the Mn^(3+)//Mn^(2+) couple is much more positive than that for Cr^(3+)//Cr^(2+) . (v) Scandium (Z = 21) does not exhibit variable oxidation states and yet it is regarded as transition element.

Assign reasons for the following : (i) Cu(I) ion is not known to exist in aqueous solutions. (ii) Transition metals are much harder than the alkali metals. (iii) From element to element, actinoid contraction is greater than the lanthanoid contraction.

Why actinoid contraction is more than lanthanoid contraction

Give an explanation for each of the following observations: (i) The gradual decrease in size (actinoid con-traction) from element to element is greater among the actinoids than that among the lanthanoids (lanthanoid contraction). (ii) The greater number of oxidation states are exhibited by the members in the middle of a transition series. (iii) With the same d-orbital (d^4) , Cr^(2+) ion is a reducing agent but Mn^(3+) ion is an oxidising agent.

(a) Complete the following chemical equations for reactions : (i) MnO_(4(aq))^(-) + S_(2)O_(3(aq))^(2-) + H_(2)O_((l)) to (ii) Cr_(2)O_(7 (aq))^(2-) + H_(2)S_((g)) + H_((aq))^(+) to (b) Give an explanation for each of the following observations : (i) The gradual decrease in size (actinoid contraction) from element to element is greater among the actinoids than that among the lanthanoids (lanthanoid contraction.) (ii) The greatest number of oxidation states are exhibited by the members in the middle of a transition series. (iii) With the same d-orbitals configuration (d^(4)) Cr^(2+) ion is a reducing agent but Mn^(3+) ion is an oxidising agent .

What is lanthanoid contraction? What are the consequences of lanthanoid contraction?

Lanthanoid contraction is due to increase in