Electronic Configuration and Octave Rule [closed]








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According to Octave rule, a shell cannot hold more than 8 electrons


But according to atomic orbitals,



> 
> The maximum number of electrons in the shell with principal quantum number `n is 2n2`.
> 
> 
> 


How do these rules reconcile?


Appreciate your help.




If you look up the time frame of the so called octave law, it is from the mid-19th century (1860s). At that time, electron did not exist, protons did not exist and the concept of atom was not clear.



> 
> According to Octave rule, a shell cannot hold more than 8 electrons
> 
> 
> 


The above statement is blatantly wrong and the textbook teaching this should be trashed. Octave rule was not meant to state this.


Anyway, the formula you quote is correct 2n$^2$.


K is shell no. 1, it can hold 2 electrons


L is shell no. 2, it can hold 8 electrons


M is shell no. 3, it can hold 18 electrons


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If exceptions are "forgotten", the teacher can teach to beginners that the octet rule works well "at least" for the $20$ first elements. And these $20$ first elements are the most frequent and most important elements found in elementary textbooks of chemistry. They contain $\ce{C, N, O, F, Na, Mg, Al, Si, P, S, Cl, K}$ and $\ce{Ca}$. These elements and the octet rule are sufficient to develop the basic theory of covalent and ionic bonds for newcomers in the world of chemistry.


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