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?