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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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अध्याय 4: d-and ƒ-Block Elements - REVIEW EXERCISES [पृष्ठ ४९२]

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Exercises | Q 4.20 (ii) | पृष्ठ ११६

संबंधित प्रश्न

What are lanthanoids?


Which among the following pairs of elements is 'not' an example of chemical twins?


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.


Write the different oxidation states of iron


What are the consequences of lanthanoid contraction?


What is meant by Lanthanide contraction? Write the general electronic configuration of inner transition elements. 


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 +3 is the characteristic oxidation state for lanthanoids but cerium also shows +4 oxidation state because:

(i) it has variable ionisation enthalpy

(ii) it has a tendency to attain noble gas configuration

(iii) it has a tendency to attain f 0 configuration

(iv) it resembles Pb4+ 


Match the property given in Column I with the element given in Column II.

  Column I (Property) Column II (Element)
(i) Lanthanoid which shows
+4 oxidation state
(a) Pm
(ii) Lanthanoid which can show +2
oxidation state
(b) Ce
(iii) Radioactive lanthanoid (c) Lu
(iv) Lanthanoid which has 4f7
electronic configuration in +3
oxidation state
(d) Eu
(v) Lanthanoid which has 4f14
electronic configuration in
+3 oxidation state
(e) Gd
    (f) Dy

On the basis of Lanthanoid contraction, explain the following:

Radii of 4d and 5d block elements.


On the basis of Lanthanoid contraction, explain the following:

Trends in acidic character of lanthanoid oxides.


How would you account for the following:

There is a greater range of oxidation states among the actinoids than among the lanthanides.


Which of the following pairs has the same ionic size?


The titanium (Z = 22) compound that does not exist is:-


In lanthanoid the last electron enters (n - 2)f subshell where n is equal to ______.


Write any two consequences of Lanthanoid Contraction.


State a reason for the following:

La(OH)3 is more basic than Lu(OH)3.


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


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