Question

The electrons first occupy the shell having ______________.

• A. the lowest energy level or K-shell and then move to the higher energy level L, M, N
• B. the lowest energy level or L-shell and then move to the higher energy level K, M, N
• C. the higher energy level or K-shell and then move to the lowest energy level L, M, N
• D. the higher energy level or L-shell and then move to the lowest energy level L, M, N

Answer 1

The correct option is A the lowest energy level or K-shell and then move to the higher energy level L, M, N

The following rules are followed for occupying the number of electrons in different energy levels or shells:

• The maximum number of electrons present in a shell is given by the formula $2n^2$, where ‘n’ is the energy level index, 1,2,3,…. Hence the maximum number of electrons in different shells are as follows:

1. First orbit or K-shell will be $=2\times 12=2$,
2. Second orbit or L-shell will be $=2\times 22=8$,
3. Third orbit or M-shell will be$=2\times 32=18$,
4. Fourth orbit or N-shell will be $=2\times 42=32$, and so on.

• The maximum number of electrons that can be accommodated in the outermost orbit is 8.
• Electrons are not accommodated in a given shell unless the inner shells are filled. That is, the shells are filled in a step-wise manner.

So from the above explanation, it is clear that the electrons occupy the shell having the lowest energy level or K-shell and then move to the higher energy shells L, M, N.