Question

Explain the rule with example according to which electrons are filled in various energy levels

Answer 1

The maximum number of electrons that can be present in any shell or orbit of an atom is given by the formula 2n², where n is the serial number of the shell.
Therefore:
K shell, n = 1, no. of electrons = 2 x 1² = 2
L shell, n = 2, no. of electrons = 2 x 2² = 8
M shell, n = 3, no. of electrons = 2 x 3² = 18
N shell, n = 4, no. of electrons = 2 x 4²= 32
Electrons are not accommodated in a given shell, unless the inner shells are filled.
That is, the shells are filled in a stepwise manner