Why do atoms follow octet rule?

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In summary: Noble gases have eight electrons in their outer shell, while elements with atomic number below 20 have a noble gas configuration by acquiring them. Transition metals don't follow the octet rule because they don't have an outer shell that can be filled with eight electrons. The d block and f block have vacant d orbitals, while hydrogen and helium do not have any 1p subshells. Additionally, ionic bonding predominates in these elements.
  • #1
abi.ayan
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when forming bond why do some atoms follow and some atoms [cations(d block )] don't follow octet rule and why does the formal charge should be lowered?
 
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Because atoms form bonds in order to get stable, i.e., attain the nearest noble gas configuration (noble gases have eight electrons in the outer shell), rather than just blindly fill their orbitals with eight electrons. They might do this by either gaining, losing or sharing electrons. The octet rule holds good only for elements with atomic number <20 because they attain noble gas configuration by doing so while transition metals won't (noble gases are p-block, ns2 np6). d and f block elements have vacant d orbitals, while hydrogen and helium do not have any 1p subshell. I've heard of some dodectet and 18-electron rule which are used to explain the bond forming of transition metals.
Lower FC indicates a better electronic distribution, which in turn increases the stability.
 
  • #3
PhysicoRaj said:
Because atoms form bonds in order to get stable, i.e., attain the nearest noble gas configuration

why does noble gas configuration stable than other configurations?
 
  • #4
Electrons have lower energy in bonds than in single atoms. So an atom will try to form as many bonds as possible.
This is counteracted by the Pauli principle, stating that electrons want to stay away from each other. Hence atoms will only form bonds if the bonds are sufficiently strong to overcome Pauli repulsion.
In the first row atoms, s and p orbitals are of approximately of the same size and energy, so that all get equally involved in bonding (thus usually 4). In higher rows, the octet rule will usually not apply as neither are s and p orbitals of same size (giving rise to different bond strength) and d orbitals (at least in main group elements) being to high in energy to participate. Furthermore, much of the bonding will be of ionic type.
In summary: The octet rule is a relic of the afterlast century and is of little relevance today in most part of chemistry.
 
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  • #5
so atoms can be stable
 
  • #6
abi.ayan said:
why does noble gas configuration stable than other configurations?

Because they contain a full valence shell of electrons.
 

1. What is the octet rule?

The octet rule is a chemical principle that states atoms tend to gain, lose, or share electrons in order to obtain a complete outermost energy level with 8 electrons, similar to the noble gas configuration. This gives the atom greater stability and makes it less reactive.

2. Why do atoms follow the octet rule?

Atoms follow the octet rule because it allows them to achieve a more stable electron configuration. By having a full outermost energy level, atoms have a lower energy state and are less likely to react with other atoms.

3. Are there any exceptions to the octet rule?

Yes, there are some exceptions to the octet rule. Atoms with fewer than 8 electrons in their outermost energy level, such as hydrogen and helium, only require 2 electrons to achieve stability. Additionally, elements in the third period or higher on the periodic table can exceed the octet rule due to the presence of d orbitals.

4. How does the octet rule affect chemical bonding?

The octet rule plays a major role in chemical bonding. Atoms will gain, lose, or share electrons in order to achieve a full outermost energy level, resulting in the formation of ionic or covalent bonds. This allows atoms to become more stable and form compounds with other elements.

5. What happens if an atom cannot follow the octet rule?

If an atom cannot follow the octet rule, it may form unstable compounds or react with other atoms to achieve a more stable electron configuration. Alternatively, the atom may undergo hybridization, where orbitals are combined to form new hybrid orbitals that allow for the bonding of atoms in a different way.

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