Question

What happens when aluminum fills its valence shell?
A) It will belong to group $17$
B) It will have 4 electrons in its outermost shell
C) It will attain noble gas configuration
D) None of these

Answer 1

We have to remember that the valence shell represents the outermost shell of an element. The electrons present in this valence shell can be termed as valence electrons. Noble gas has a stable electronic configuration i.e. completely filled orbitals and it belongs to the group $18$.

Complete step by step answer:
We are going to calculate electronic configuration for $Al$ first.
We have to know that the electronic configuration of Aluminum is $1{s^2}2{s^2}2{p^6}3{s^2}3{p^1}$
Symbol: $Al$
Atomic number: $13$
In order to write the electronic configuration of $Al$, we need to know the number of electrons in an element, Since Atomic number= No. of electrons
Thus, the total number of electrons $= 13$, so to write the configuration we need to fill the orbitals around the$Al$atom.
Since, $s$ orbital can hold up to $2$ electrons so we will start filling the electrons from $1s$ orbital to $2s$ orbital. Now comes p orbital, $6$ electrons can be filled in p orbital thus $2p$ orbital will be filled next. Then we will move to the next orbital i.e. $3s$ followed by $3p$ on the basis of its electron capacity and the no. of electrons left for filling.
So,
Electronic configuration: $1{s^2}2{s^2}2{p^6}3{s^2}3{p^1}$
Now what happens if the outermost shell of Aluminum is filled completely, i.e.
Electronic configuration will turned out to be- $1{s^2}2{s^2}2{p^6}3{s^2}3{p^6}$, which is the configuration of noble gases that means $Al$ will attain its stability as noble gas which belongs to group 18 in periodic table.
Option A) is incorrect as when $Al$ fills up its electron according to group $17$ i.e. Halogen will have this configuration$1{s^2}2{s^2}2{p^6}3{s^2}3{p^5}$.
Option B) is incorrect as on filling up its outermost shell completely it will have $8$ electrons in it.
Option C) is correct as, the stable noble gas configuration is $1{s^2}2{s^2}2{p^6}3{s^2}3{p^6}$ so when outermost shell for $Al$ is filled completely it will attain noble gas configuration.
Option D) is incorrect since Option C) turns out to be right.

Hence, Option C is the correct answer.

Note: As we know that the noble gas configuration is $1{s^2}2{s^2}2{p^6}3{s^2}3{p^6}$ in which all the orbitals are completely filled and the elements of group $18$ does not react with others due to having completely filled outermost orbital. Group $17$ belongs to Halogen family having one electron less in its outermost shell leading to an electronic configuration $1{s^2}2{s^2}2{p^6}3{s^2}3{p^5}$.