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This is because inert pair effect is maximum in thallium in which poor shielding of the s-electrons of the valence shell (6s 2 ) by the 3d, -4d, -5d and 4f-electron occurs. As a result, only 6p 1 electron participates in bond formation and thus the most stable oxidation state of Tl is +1 and not +3. Therefore, TlCl is stable while TlCl 3 is unstable. On the other hand, all the three valence electrons (2s 2 2p 1 ) of boron take part in the bond formation due to the absence of d–and f-electrons in B(no inert pair effects). Hence B shows an oxidation state of +3 and thus forms BCl 3 easily. Thus BCl 3 is more stable than TlCl 3 .

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The p-Block Elements

Short Answer Type

61.

Complete the following reaction equation:
$straight R subscript 2 SiCl subscript 2 space plus space straight H subscript 2 straight O space rightwards arrow$

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Long Answer Type

62. How do elements of group 13 occur in nature?

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63.

Discuss the characteristics of group 13 elements in terms of:
(i) Atomic and ionic radii
(ii) ionisation enthalpy
(iii) Density, melting point and boiling points.

698 Views

Short Answer Type

64.

How would you explain the lower atomic radius of Ga as compared to Al ?

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Long Answer Type

65. Discuss the characteristics of group 13 elements in terms of :
(i) Electronegativity
(ii) Nature of bonds
(iii) Oxidation states.

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66.

Explain the following:
(i) Boron is trivalent
(ii) Boron and aluminium tend to form covalent compounds.

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67.

Discuss the pattern of variation in the oxidation states of B(Boron) to Tl(Thallium).
Or
What is inert pair effect? Illustrate it with reference to Boron family.

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Short Answer Type

68.
How can you explain the higher stability of BCl₃ as compared to TlCl₃?

This is because inert pair effect is maximum in thallium in which poor shielding of the s-electrons of the valence shell (6s²) by the 3d, -4d, -5d and 4f-electron occurs. As a result, only 6p¹ electron participates in bond formation and thus the most stable oxidation state of Tl is +1 and not +3. Therefore, TlCl is stable while TlCl₃ is unstable.
On the other hand, all the three valence electrons (2s²2p¹) of boron take part in the bond formation due to the absence of d–and f-electrons in B(no inert pair effects). Hence B shows an oxidation state of +3 and thus forms BCl₃ easily. Thus BCl₃ is more stable than TlCl₃.

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69.

Standard electrode potential values $straight E to the power of circled dash space for space Al to the power of 3 plus end exponent divided by Al space is space minus 1.66 straight V$ and that of $Tl to the power of 3 plus end exponent divided by Tl$ is +1.26 V. Predict about the formation of M³⁺ ion in solution and compare the electropositive character of the two metals.