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Physical Chemistry

Blazing goIITian

Joined:	4 May 2007
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7 Dec 2007 13:37:24 IST

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what is inert pair effect?

None

how does it effct the properties of the elements?

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Blazing goIITian

Joined: 3 Aug 2007

Posts: 603

7 Dec 2007 16:09:56 IST

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it is unreactiveness of s electrons, in the atoms of p block belonging to 4th, 5th and 6th periods.
down the periodic table, it increases.
thus stability
Ge2+ < Ge4+
but Pb2+ > Pb4+

also Ge2+ < Sn2+ < Pb2+

Prashant Sahu

Cool goIITian

Joined: 15 Mar 2007

Posts: 92

12 Dec 2007 11:52:29 IST

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Inert pair effect:

1. It is the reluctance of the s-electrons of the valence shell to take part in bonding and occurs due to ineffective shielding of the ns² electrons by the intervening d and f electrons.

2. It increases down a group and thus the lower elements of group show lower oxidation states, actually 2-less oxidation state, than the upper ones.

3. B and Al show an oxidation state of +3 only while Ga, In and T1 show oxidation states of both and +3.

4. As we move down in the group 13, due to inert pair effect, the tendency to achieve +3 oxidation state goes on decreasing and the tendency to acquire +1 oxidation state goes on increasing.

5. Stability of +1 oxidations ate follows the order Ga < In < Tl.

6. Tl⁺ compounds are more stable than Tl³⁺. Tl₂O and TlCl are more stable than Tl₂O₃ and TlCl.

7. The compounds of Ge and Sn in +2 oxidation state are reducing in nature. Since their higher oxidation states +4 are more stable.

8. The compounds of Pb in +4 oxidation state are powerful oxidizing in nature. Since +2 oxidation state of Pb is more stable.

9. The compounds in +2 oxidation state are ionic in nature and in +4 oxidation state are covalent in nature (Fajan's Rule).

10. Similarly, Bi³⁺ is more stable than Bi⁵⁺.

11. Po (IV) is more stable than Po (VI). Po does not form oxide PoO₃, but it forms PoO₂, unlike other elements of the same gp. S forms SO₂ ans SO₃, Se forms both SeO₂ and SeO₃, Te forms TeO, TeO₂, and TeO₃, but Po forms only PoO and PoO₂. It doesn't forms PoO₃.

Hope this clears ur doubt.

Priyesh

Blazing goIITian

Joined: 18 Feb 2007

Posts: 1042

12 Dec 2007 18:53:51 IST

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The reason for this effect in covalent bond formation is that for heavier elements promotion of electron from s orbital to p orbital is more than the energy released during bond formation rendering the promotion of s - electron unstable

that is why in lead +2 state is more stable than +4 because it does not promote it's s-electrons to p orbital.

for ionic bonds explanation is given that for the heavier elements like lead, there is what is known as a relativistic contraction of the electrons which tends to draw the electrons closer to the nucleus than you would expect. Because they are closer to the nucleus, they are more difficult to remove. The heavier the element, the greater this effect & this affects s electrons much more than p electrons.

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