Question

The electronic configuration of aluminium is:
(A)- K = 2, L = 8, M = 3
(B)- K = 1, L = 2, M = 8, N = 3
(C)- P = 2, Q = 8, R = 3
(D)- None of the above

Answer 1

K, L, M, N represents the number of principle shells of the atom and the order of their increasing energy is K < L < M < N and each shell has a specific capacity to keep the electrons.

Complete step by step solution:
The electronic configuration of the element tells the number of electrons in each shell of the orbit. K, L, M, N represents the number of principle shells of the atom and the order of their increasing energy is K < L < M < N < … and each shell has a specific capacity to keep the electrons.
So, the K represents shell number 1 and tells that this shell is closest to the nucleus, L represents shell number 2, M represents shell number 3, and so on.
So aluminium is the element of the p-block and belongs to the group 13, therefore, the atomic number of aluminium is 13. Its electronic configuration is $1{{s}^{2}}2{{s}^{2}}2{{p}^{6}}3{{s}^{2}}3{{p}^{1}}$.
So the total number of electrons in 1st shell is 2 i.e., in K, the total number of electrons in 2nd shell is 8 (2+6) i.e., in L, and the total number of electrons in 3rd shell is 3 (2+1) i.e., in M.
So its configuration will be K = 2, L = 8, M = 3

Therefore, the correct answer is option (A)- K = 2, L = 8, M = 3.

Note: Each shell can accommodate only a specific number of electrons i.e., the maximum number of the electron that can enter in K shell is 2, the maximum number of the electron that can enter in L shell is 8, the maximum number of electrons that can enter in M shell is 18 and so on.