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प्रश्न
The chemistry of the actinoid elements is not so smooth as that of the Lanthanoids. Justify this statement by giving some examples from the oxidation state of these elements.
उत्तर
The oxidation states of lanthanoids are +2, +3 and +4. Of these, +3 is the most common state. The limited number of oxidation states is due to the large energy difference between the 4f, 5d and 6s sub-orbitals. In contrast, actinoids show many oxidation states, such as +2, +3, +4, +5, +6 and +7, although their most common state is +3. This is because there is a small energy difference between the 5f, 6d and 7s sub-orbitals.
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संबंधित प्रश्न
Which among the following pairs of elements is 'not' an example of chemical twins?
What are the different oxidation states exhibited by the lanthanoids?
Write the different oxidation states of iron
Answer the followiiig questions:
Which trivalent ion has maximum size in the Lanthanoid series i.e. Lanthanum ion (La3+) to Luteium ion (Lu3+)?
(at. no. of Lanthanum = 57 and Lutetium = 71)
Name an element of lanthanoid series which is well knwon to shown +4 oxidation state. Is it a strong oxidising agent or reducing agent?
What is meant by Lanthanide contraction? Write the general electronic configuration of inner transition elements.
What is Lanthanoid contraction?
Match the statements given in Column I with the oxidation states given in Column II.
| Column I | Column II | |
| (i) | Oxidation state of Mn in MnO2 is | (a) + 2 |
| (ii) | Most stable oxidation state of Mn is | (b) + 3 |
| (iii) | Most stable oxidation state of | (c) + 4 |
| Mn in oxides is | (d) + 5 | |
| (iv) | Characteristic oxidation state of lanthanoids is | (e) + 7 |
On the basis of Lanthanoid contraction, explain the following:
Stability of the complexes of lanthanoids.
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?
Cerium (Z = S8) is an important member of lanthanoids. Which of the following statements about cerium is incorrect?
Why is Mn2+ ion more stable than Fe2+ ion?
(Atomic numbers of Mn = 25 and Fe = 26)
Trivalent Lanthanoid ions such as La3+ (Z = 57) and Lu3+ (Z = 71) do not show any colour in their solution. Give a reason.
Assertion: There is a continuous increase in size among Lanthanoids with an increase in atomic number.
Reason: Lanthanoids do not show Lanthanoid contraction.
Name an important alloy which contains some of the lanthanoid metals.
