Question

What element has a noble gas notation [Xe]$6s^2$?

Answer 1

Hint: Attempt this question by finding out the atomic number and number of electrons in a Xenon (Xe) atom followed by calculating the total number of electron in the noble gas notation [Xe]$6s^2$ and then further find out the element with the respective configuration.

Complete answer:
Let us first discuss about electronic configuration:-
-As we know that electron configuration of an element tells us about how electrons are distributed in its atomic orbitals. It follows a standard notation in which all atomic sub shells containing electrons (where the number of electrons they hold are written in superscript) are placed in a sequence.
-The standard notation often seems to be lengthy electron configurations (especially in case of elements having a relatively large atomic number). In these cases, an abbreviated notation can be used instead of the standard notation. In the abbreviated notation, the sequence of completely filled subshells which correspond to the electronic configuration of the nearby noble gas is replaced with the symbol of the same nearby noble gas in square brackets.
-We are given [Xe]$6s^2$, so first let us calculate the number of electrons in xenon atom:-
The atomic number of Xenon is = 54
As we know that the atomic number of an atom is equal to the number of protons as well as number of electrons in that atom.
Therefore number of electrons in Xenon (Xe) = 54
-Total number of electrons in [Xe]$6s^2$= 54 + 2 = 56
Since the number of electrons is 56 which means the atomic number of the element will also be 56 and barium is the element whose atomic number is 56.
-Hence, Barium is the element whose noble gas notation is [Xe]$6s^2$.

Note:
-The standard electronic configuration for Barium (Ba) is: $1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}3d^{10}4s^{2}4p^{6}4d^{10}5s^{2}5p^{6}6s^2$which is an alkaline earth metal and has a +2 valency. Here $1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}3d^{10}4s^{2}4p^{6}4d^{10}5s^{2}5p^6$is the electronic configuration for Xenon (Xe).
-Also we must learn the periodic table along with the atomic number of elements, especially of noble gas elements.