Question

The electronic configuration of the outermost orbit in the case of alkaline earth metal is
A) \[\]\[n{{s}^{2}}\]
B) \[n{{s}^{2}}n{{p}^{1}}\]
C) \[n{{s}^{1}}\]
D) \[n{{s}^{2}}n{{p}^{4}}\]

Answer 1

Hint: The alkaline earth metal elements belong to s- block elements
- It is the second group in the periodic table.

Complete Solution :
So in the question we have to find the electronic configuration of the outermost orbit for the alkaline earth metals.
- So we know that every group has its own general electronic configuration.
Now let’s see where the alkaline earth metals are placed in the periodic table.
The alkaline earth metals are placed in the extreme left side of the periodic table. It is the second group element.
We know that the first two groups in the periodic table belong to s-block elements, it is called so since the valence electron enters in the outermost s-orbital.
So now we know both the groups i.e. first and second group elements have s- orbitals as their outer –most shells.
Now we have found the difference between these two groups. Let’s write the electronic configuration of the alkaline earth elements.
The alkaline earth elements are –Be, Mg, Ca, Sr, Ba, Ra
$\begin{align}
 & _{4}Be=\left[ He \right]2{{s}^{2}} \\
 & _{12}Mg=\left[ Ne \right]\,\,3{{s}^{2}} \\
 & _{20}Ca=\left[ Ar \right]4{{s}^{2}} \\
 & _{38}Sr=\left[ Kr \right]5{{s}^{2}} \\
 & _{56}Ba=\left[ Xe \right]6{{s}^{2}} \\
 & _{88}Ra=\left[ Rn \right]7{{s}^{2}} \\
\end{align}$

So if we look into the electronic configurations all these elements, all the elements have s –orbitals with various shell number and the outermost valence shell have 2 electrons in them i.e. \[n{{s}^{2}}\] is the configuration of the outermost shell.
So, the correct answer is “Option A”.

Additional Information. The elements of the group 2 are called alkaline earth metals, since their oxides generally occur in earth crust and they are alkaline in nature.
The metals are very reactive so they are not found free in nature

Note: The general electronic configuration is set according to the number of electrons in the valence orbitals and the element possesses a valency similar to its electrons in the outermost shell.
There is a change of getting confused with the electronic configuration with alkali metals.
- But the alkali metals and alkaline earth metals are different. Alkali metals are the first elements in the first group, with the s orbital as the outermost orbital having an electronic configuration of \[n{{s}^{1}}\]