Question

Electronic configuration of magnesium is
A. 2, 8, 2
B. 2, 8, 1
C. 2, 8, 7
D. 2, 1

Answer 1

Hint: We first find the atomic number of magnesium. The atomic number of an element is only the quantity of electrons in the element. That point we find the electronic configuration of the given element by following the Aufbau Principle, Pauli exclusion principle and Hand's rule to fill the electrons.

Complete step by step answer:
-Shells: The greatest number of electrons that can be accommodated in a shell depends on the central quantum number (n). It is represented by the 2n2, where 'n' is the shell number. For n=1(K shell) no. of electrons= 2
-Subshells: The subshells into which electrons are distributed and based on the azimuthal quantum number (signified by 'l'). This quantum number is dependent on the value of the main quantum number, n. Along these lines, when n has a value of 4, four different subshells are possible. When n=4. The subshells compare to l=0, l=1, l=2, and l=3 and are named the s, p, d, and f subshells respectively. The max number of electrons that can be accommodated by a subshell is given by the equation \[2(2l+1)\] . Hence, the s, p, d, and f subshells can accommodate a max of 2, 6, 10, and 14 electrons respectively.
With the help of these subshell labels, the electron configuration of magnesium (atomic number 12) can be composed as \[1{{s}^{2}}2{{s}^{2}}2{{p}^{6}}3{{s}^{2}}\].
2 in K shell, 8 in L shell and 2 in M shell.
In this way, electronic configuration is 2, 8, 2.
So, the correct answer is “Option A”.

Note:
The possible mistakes that can be made while solving this kind of question are, One may not follow Aufbau rule carefully to get the right configuration. One needs to follow Aufbau rule effectively to find the final answer.