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Prince Singh Grade: 10
        

is the octate rule was not succesfull?

5 years ago

Answers : (2)

Revanth - -
36 Points
										

it was unsuccessful.


OCTET RULE









The arrangement of the chemical elements in the PERIODIC TABLE is explained by the way in which electrons fill the available energy levels, or shells, in atoms. In particular, the noble gases, such as neon, xenon and argon, have eight electrons in their outermost shell, which is why they do not easily engage in chemical reactions.

According to octet rule atoms gain, lose or change valence electrons in order to end up with eight valence electrons. The effect that this has is of providing the same stable electron arrangement as found in inert gases.

This rule explains how atoms form ions. Take sodium as an example, it has 11 electrons 2 in the innermost shell 8 in the next and 1 in the outermost shell. The outermost electron is easy to remove so that when energy is added to the sodium atom a sodium ion with one positive charge is easily formed. It takes ten times as much energy to remove an electron from an inner shell, however so a sodium ion with a double positive charge is rarely seen. In the same way calcium an atom with 2 electrons in its outermost shell and 8 in the next lower one forms an ion by losing two electrons. Thus when atoms become ions, they tend to resemble noble gas atoms.



 



Exceptions to the octet rule




Many molecules composed of atoms of the main group elements have electronic structures that satisfy the octet rule, but a number of them do not. A few molecules such as NO having odd number of electrons cannot satisfy the octet rule.

Other exceptions of octet rule fall into two groups-one a group of molecules with an atom having fewer than eight valence electrons around it and the other a group of molecules with an atom having more than eight valence electrons around it. The exceptions in which the central atom has more than eight valence electrons around it are fairly numerous.

The octet rule does not apply to group I-B-7-B elements most of which form ions with two or more different positive charges. Copper, for example can lose one valence electron to form Cu+ alternatively it can lose two valence electrons to form Cu2+

Although octet rule is successful in explaining the valencies of large number of elements yet it fails to explain many of the structures. Some of the limitations are

  1. Formation of compounds with electron deficient atoms.

  2. Formation of super octet molecules like PCl5, SF6 and IF7.

  3. Formation of compounds of xenon.

  4. Inability to predict the energy changes.

5 years ago
Monil Shah
34 Points
										

yes the octet rule was successful because it could explain almost all the compoiunds at that time and exceptions do exist...


like if answer is good...

5 years ago
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