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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 5f electrons are more effectively sheilded from nuclear charge. In other workds the 5f electrons themselves provide poor shelding from element to element in the series.
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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

RESONANCE ENGLISH-D & F-BLOCK ELEMENTS & THEIR IMPORTANT COMPOUNDS -Exercise 1
  1. Write balanced chemical equations for: (i) Mixture of K(2)Cr(2)O(7) ...

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  2. What are inner transition elements? Decide which of the following atom...

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  3. Actinoid contraction is greater from element to element than lanthanoi...

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  4. The chemistry of the actinoid elements is not so smooth as that of the...

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  5. Why Sm^(2+) , Eu^(2+) and Yb^(2+) ions are good reducing agents , but ...

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  6. The transition elements have a general electronic configuration.

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  7. The atomic volume of the transition elements are low compared with ele...

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  8. The wrong statement regarding transition metals among the following is...

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  9. First IE of 5d seties element are higher than those of 3d and 4d serie...

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  10. Ionisation energies of Ni and Pt in Kjmol^(-1) are given below {:(,u...

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  11. Maximum oxidation state is shown by:

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  12. Which of the following statement is false?

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  13. Which of the following has the maximum number of unpaired d-electron?

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  14. Highest magnetic moments, shown by the transition metal ion with the ...

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  15. Magnetic moment of Cr^(+2)(Z=24),Mn^(+2)(Z=25) and Fe^(2+) (Z=26) are ...

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  16. Spin only magnetic moment of .(25)Mn^(x+)ion is sqrt(15) B.M. Then, t...

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  17. Colour in transition metal compounds in attributed to

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  18. MnO(4)^(-) is of intense pink colour, though Mn is in (+7) oxidation s...

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  19. The yellow colour of chromates changes to orange on acidification due...

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  20. The catalytic activity of transition metals and their compounds is asc...

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