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कर्नाटक बोर्ड पी.यू.सी.पीयूसी विज्ञान 2nd PUC Class 12

Compare the chemistry of actinoids with that of the lanthanoids with special reference to atomic and ionic sizes.

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प्रश्न

Compare the chemistry of actinoids with that of the lanthanoids with special reference to atomic and ionic sizes.

दीर्घउत्तर
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उत्तर

Both lanthanoids and actinoids show a progressive decrease in the size of their atoms and ions (M3+) across the series. In lanthanoids, this decrease is called lanthanoid contraction, while in actinoids, it is called actinoid contraction.
However, the decrease in size between two successive elements is higher in actinoids than in lanthanoids (i.e., actinoid contraction is more pronounced than lanthanoid contraction). This is because 5f electrons provide a poorer screening/shielding effect than 4f electrons, causing the outer electrons in actinoids to experience a stronger effective nuclear charge.
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पाठ 4: d-and ƒ-Block Elements - REVIEW EXERCISES [पृष्ठ ४९२]

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संबंधित प्रश्‍न

What are lanthanoids?


Name a member of the lanthanoid series which is well known to exhibit +4 oxidation state.


Compare the chemistry of actinoids with that of lanthanoids with special reference to electronic configuration.


Compare the chemistry of actinoids with that of the lanthanoids with special reference to chemical reactivity.


Explain effects of lanthanoid contraction.


Account for the following: 

Zn, Cd and Hg are soft metals.


Explain the cause of Lanthanoids contraction.


The f-block elements are known as ____________.


Gadolinium belongs to 4f series. It’s atomic number is 64. Which of the following is the correct electronic configuration of gadolinium?


General electronic configuration of actinoids is `(n-2)f^(1-14)(n - 1)d^(0-2)ns^2`.Which of the following actinoids have one electron in 6d orbital?

(i) U (Atomic no. 92)

(ii) Np (Atomic no.93)

(iii) Pu (Atomic no. 94)

(iv) Am (Atomic no. 95)


Although Zr belongs to 4d and Hf belongs to 5d transition series but it is quite difficult to separate them. Why?


Although +3 oxidation states is the characteristic oxidation state of lanthanoids but cerium shows +4 oxidation state also. Why?


Match the compounds/elements given in Column I with uses given in Column II.

  Column I (Compound/element) Column II (Use)
(i)  Lanthanoid oxide (a) Production of iron alloy
(ii)  Lanthanoid (b) Television screen
(iii)  Misch metal (c) Petroleum cracking
(iv)  Magnesium based alloy is constituent of (d) Lanthanoid metal + iron
(v)  Mixed oxides of lanthanoids are employed (e) Bullets
    (f) In X-ray screen

On the basis of Lanthanoid contraction, explain the following:

Trends in the stability of oxo salts of lanthanoids from \[\ce{La}\] to \[\ce{Lu}\].


On the basis of Lanthanoid contraction, explain the following:

Stability of the complexes of lanthanoids.


Which of the following pairs has the same ionic size?


Write any two consequences of Lanthanoid Contraction.


Write a note on lanthanoids.


Name an important alloy which contains some of the lanthanoid metals. Mention its uses.


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