Question

What are the rules to be followed for writing the number of electrons in different energy level or Shell and why

Answer 1

(i)The maximum number of electrons present in a shell is given by the formula 2n², where ‘n’ is the orbit number or energy level index, 1, 2, 3…

(ii)The maximum number of electrons that can be accommodated in the outermost orbit is 8.

(iii)Electrons are not accommodated in a given shell, unless the inner shells are filled.

Examples:

Electronic configuration of the element having atomic number 6 = 2, 4

Electronic configuration of the element having atomic number 11 = 2, 8, 1

Electronic configuration of the element having atomic number 15 = 2, 8, 5

Electronic configuration of the element having atomic number 18 = 2, 8, 8


These rules are based on the observations of Niel Bohr, and that is the reason why we need to follow them.