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Question
What are lanthanoids?
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Solution
The series involving the filling of 4f-orbitals following lanthanum La (Z = 57) is called the lanthanoid series. The elements present in this series are called lanthanoids.
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RELATED QUESTIONS
Define lanthanoid contraction.
What are chemical twins? Write ‘two’ examples.
Which among the following pairs of elements is 'not' an example of chemical twins?
What are the different oxidation states exhibited by the lanthanoids?
Explain effects of lanthanoid contraction.
What are the consequences of lanthanoid contraction?
The f-block elements are known as ____________.
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+
Although Zr belongs to 4d and Hf belongs to 5d transition series but it is quite difficult to separate them. 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 |
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 |
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?
In lanthanoid the last electron enters (n - 2)f subshell where n is equal to ______.
Zr (Z = 40) and Hf (Z = 72) have similar atomic and ionic radii because of ______.
Write any two consequences of Lanthanoid Contraction.
The lathanide ion that would show colour is ______.
Mischmetal is an alloy consisting mainly of ______.
Assertion: There is a continuous increase in size among Lanthanoids with an increase in atomic number.
Reason: Lanthanoids do not show Lanthanoid contraction.
The pair of lanthanoid ions which are diamagnetic is:
