How can we distribute atoms in shell
According to Neils Bohr’s postulates, electrons are revolving around the nucleus along a specific pathway called orbits/shells. He called these orbits/shells as energy levels and represented them by letters and numbers like K, L, M, N, O,… and n= 1, 2, 3, 4,…respectively.
Neils Bohr and Bury suggested the distribution and arrangement of electrons in different shells. The distribution of electrons among the different orbits/shells and sub-shells is known as the electronic configuration of an atom. Generally, the electronic configuration represents the electron distribution, when an atom is at the ground state. There are certain rules to be followed for the distribution of electrons among different shells.
you will study more in higher classes. Neil Bohr's theory is widely accepted. You'll learn different theories in details in higher Classes.
good luck