Question

What is the shorthand electron configuration of $Xe$ ?

Answer 1

We know that the elements which are known by the terms mentioned in the options. We have to identify the element from the given electronic configuration Look at the electronic configuration and find out in which orbital the valence electrons are present. Find out how many electrons are present in the valence shell to get the answer.

Complete answer:
Xenon is element $54,$in the noble gases (last) column. To get the short-handed electron configuration, look at the noble gas in the row above xenon. This would be krypton. This is the base that we use to form the configuration. So far, we have $\left[ Kr \right].$
Now, let's look at the row for Xenon. Since it is in row $5,$ we will be filling the $5s$ and $5p$ orbitals. Remember that the d orbitals start at $3d$ in row $4,$ so we will be filling the $4d$ orbitals. Starting from left to right, we fill in $2$ electrons for the s orbitals. Since we haven't gotten to xenon yet, we need to fill in the d orbitals. This will be $10$ electrons. We need to fill in the p orbitals to complete the configuration. We will fill all $6$ electrons in. Now we got the electron configuration for xenon. The complete electronic configuration is $1{{s}^{2}}2{{s}^{2}}2{{p}^{6}}3{{s}^{2}}3{{p}^{6}}4{{s}^{2}}3{{d}^{10}}4{{p}^{6}}5{{s}^{2}}4{{d}^{10}}5{{p}^{6}}$.
We can see that the $5d$ orbital is incompletely filled. This indicates that the given element belongs to d-block and not s-block. So, this element is not an alkaline earth metal. It has the valence shell $6s$ which means the element belongs to the sixth period. We know that lanthanides are present in the sixth period. $~\left[ Kr \right]~4{{d}^{10}}5{{s}^{2}}5{{p}^{6}}$ here, $4d$ orbitals are lower in energy than $5s,$ so $4d$ electrons are typically listed before $5s$ electrons.

Note:
Remember that the given element has completely filled $4f$ orbitals and $3$ electrons left to complete 5d orbitals, which means, this element is not a lanthanide and thus, not a rare earth element. This element has a vacant $6p$ orbital, so it is not an inert gas element. So, three out of four options are eliminated. Therefore, our answer should be the transition element which is correct because d-block elements are transition elements.