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प्रश्न
Explain the cause of Lanthanoids contraction.
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उत्तर
- In the Lanthanoid series with increasing atomic number, the atomic and ionic radii decrease from one element to another but a decrease is very small.
- An increase in nuclear charge in a period increases the force of attraction towards the outer electrons. Hence
atomic size or radius decreases. - Filling of the electrons in the inner shells increases the atomic size as inner electrons repel outer electrons. The shielding effect of electrons decreases in the order s > p > d > f
- The new electrons are added to the same inner 4f orbital. Hence, Lanthanoid contraction is due to
- Poor shielding effect of the 4f electrons
- Increase in nuclear charge.
- Non-introduction of new outer shells.
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संबंधित प्रश्न
Define lanthanoid contraction.
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 atomic and ionic sizes.
Write the electronic configuration of the element with the atomic number 61.
Write the different oxidation states of iron
Explain effects of lanthanoid contraction.
Account for the following:
Zn, Cd and Hg are soft metals.
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.
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?
Which of the following lanthanoids show +2 oxidation state besides the characteristic oxidation state +3 of lanthanoids?
(i) \[\ce{Ce}\]
(ii) \[\ce{Eu}\]
(iii) \[\ce{Yb}\]
(iv) \[\ce{Ho}\]
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 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:
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.
On the basis of Lanthanoid contraction, explain the following:
Radii of 4d and 5d block elements.
How would you account for the following:
There is a greater range of oxidation states among the actinoids than among the lanthanides.
Write any two consequences of Lanthanoid Contraction.
Mischmetal is an alloy consisting mainly of ______.
State a reason for the following:
La(OH)3 is more basic than Lu(OH)3.
Trivalent Lanthanoid ions such as La3+ (Z = 57) and Lu3+ (Z = 71) do not show any colour in their solution. Give a reason.
Name an important alloy which contains some of the lanthanoid metals.
Name an important alloy which contains some of the lanthanoid metals. Mention its uses.
The pair of lanthanoid ions which are diamagnetic is:
