Why do atoms follow octet rule?

  • Thread starter Thread starter abi.ayan
  • Start date Start date
  • Tags Tags
    Atoms
Click For Summary

Discussion Overview

The discussion revolves around the octet rule and its applicability to different elements, particularly in the context of atomic bonding and stability. Participants explore why some atoms, especially transition metals, do not adhere to the octet rule and the implications of formal charge on stability.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • Some participants propose that atoms bond to achieve stability by attaining a noble gas configuration, which typically involves having eight electrons in the outer shell.
  • Others argue that the octet rule is primarily applicable to elements with atomic numbers less than 20, while transition metals and d-block elements do not follow this rule due to their vacant d orbitals and different bonding characteristics.
  • A participant mentions the concept of lower formal charge indicating better electronic distribution, which may enhance stability.
  • One participant questions why noble gas configurations are considered more stable than other configurations, suggesting that full valence shells contribute to this stability.
  • Another participant discusses the energy dynamics of electrons in bonds versus single atoms, referencing the Pauli principle and the varying sizes and energies of orbitals in different rows of the periodic table.
  • It is noted that the octet rule may be less relevant in modern chemistry, particularly for higher rows of elements where bonding characteristics differ significantly.

Areas of Agreement / Disagreement

Participants express differing views on the applicability and relevance of the octet rule, particularly concerning transition metals and the nature of stability in noble gas configurations. No consensus is reached on these points.

Contextual Notes

Some limitations include the dependence on atomic number and orbital characteristics, as well as the unresolved nature of how bonding dynamics differ across the periodic table.

abi.ayan
Messages
37
Reaction score
0
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?
 
Chemistry news on Phys.org
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.
 
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?
 
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.
 
  • Like
Likes   Reactions: 1 person
so atoms can be stable
 
abi.ayan said:
why does noble gas configuration stable than other configurations?

Because they contain a full valence shell of electrons.
 

Similar threads

Rationale for 6n+2 rule for the number of pi bonds in a non-cyclic molecule
  • · Replies 3 ·
Replies
3
Views
2K
How Does SO3 Form 3 Pi Bonds Without an Expanded Octet Structure?
  • · Replies 2 ·
Replies
2
Views
3K
Why does NH3 turn into NH4+? Also question about bond EN.
  • · Replies 7 ·
Replies
7
Views
5K
Why do atoms want to complete their shells?
  • · Replies 6 ·
Replies
6
Views
2K
In coordinate bond, why doesn't the H^+ atom get a negative charge?
  • · Replies 32 ·
2
Replies
32
Views
5K
Heterolytic and Homolytic Cleavage
  • · Replies 1 ·
Replies
1
Views
2K
Chemistry Why Does IF5 Exhibit a Square Pyramidal Shape Despite Exceeding the Octet Rule?
  • · Replies 1 ·
Replies
1
Views
3K
Lewis dot structure, octet rule for a central atom
  • · Replies 1 ·
Replies
1
Views
3K
What is the Lewis structure of C3H5+ ion?
  • · Replies 5 ·
Replies
5
Views
6K
Why Do Atoms Need to Have Free Electrons to Create Covalent Bonds?
  • · Replies 14 ·
Replies
14
Views
3K