Question

What is the electronic configuration of elements IIIrd of group 13?
A.$1{s^2}2{s^2}2{p^3}$
B.$1{s^2}2{s^2}2{p^6}3{s^2}3{p^1}$
C.$1{s^2}2{s^2}2{s^6}$
D.$1{s^2}2{s^2}2{s^6}3{s^1}$

Answer 1

We need to understand the position of the elements in the periodic table to answer this question. Group 13 is in the p-block of the periodic table and it consists of Boron, Aluminium, Gallium, Indium, and Thallium. This group is also known as the Boron Family and has one electron in its outer p-orbital.

Complete answer:
The question asks us to find the electronic configuration of the element in the third period of group 13. We know that the element in the third period of group 13 is Aluminium and it has an atomic number of 13. We can use the Aufbau principle to find out the electronic configuration of Aluminum.
According to the Aufbau principle, we have to fill the orbitals in the increasing order of their energy and thus we will have the following order.
$1s < 2s < 2p < 3s < 3p$
Thus we can fill the 13 electrons of aluminium in this order and thus we will obtain the following electronic configuration.
$1{s^2}2{s^2}2{p^6}3{s^2}3{p^1}$
Thus the correct option for this question will be (B).

Note:
In this question option (C) and option (D) can be easily eliminated at the first glance because it disobeys a fundamental principle. The s orbital can hold only a maximum of 2 electrons. In both of these options, there are 6 electrons being given to the s orbital which is wrong. Option (A) can also be eliminated because the total electrons in that option do not add up to 13 and thus cannot be the electronic configuration of Aluminium.