Why do octets lead to a stable configuration?

[Shrijit Roy]

Hey everyone!
I am currently learning about the stability of an atom. I have learnt that octet or duet rule leads to stable electronic configuration but what I do not understand is why only these two configurations make stable electronic configurations? Why can't an atom be stable with any other configurations? Can someone please break it down for me? Thank you so much for the help!

 

[Borek]

These numbers reflect internal structure of the orbitals, and as such stem from the Schroedinger's equation solutions. 2, 8 and 18 are numbers of electrons that can occupy one energy shell - and if the shell is full of electrons, it is more stable than when it is not.

Technically these numbers apply directly to atoms only, but in reality solutions of the Schroedinger's equation for molecules are often variations of the solutions for atom, so these numbers appear quite often.

 

[Shrijit Roy]

These numbers reflect internal structure of the orbitals, and as such stem from the Schroedinger's equation solutions. 2, 8 and 18 are numbers of electrons that can occupy one energy shell - and if the shell is full of electrons, it is more stable than when it is not.

Technically these numbers apply directly to atoms only, but in reality solutions of the Schroedinger's equation for molecules are often variations of the solutions for atom, so these numbers appear quite often.

I am a beginner with barely any idea of quantum physics. Could you please explain in simpler terms?

 

[Zaciekawiony]

In atoms, systems with closed electron shells have the highest stability. Elements with valence electrons in the s and p shells, i.e., from the main groups, tend to have an octet, because that is the number of electrons in the second shell. D-block elements tend to form the most stable complexes in the 18-electron system.

 

[Borek]

I am a beginner with barely any idea of quantum physics. Could you please explain in simpler terms?

I am afraid at this level you need to just accept the general picture as such, any explanation will just produce more "why" questions which are not easy to answer without delving into details. Electrons occupy orbitals, number of electrons per orbital is limited to two, these orbitals are described using four small integer numbers (there are some rules that tell which combinations of values are correct and possible), energy shell are all orbitals that have the same principal quantum number. Letters s, p and d Zaciekawiony mentioned are related to another of these quantum numbers, but as I said - they will be hardly explaining anything if you have no idea what they refer to.