why are the shells called k,l,m,n?

Hi,

 

Bohr classified various energy states as energy shells .they were named as K , L , M, N….they were named as such with the sequence .there was no any special meaning behind it, as you can name things like x , y, z, Bohr named them as K,L, M..This is now considered a standard notation to address the energy shells.

 

Hope it helps.

Cheers!