Question

What element is represented $[Kr]5{{s}^{1}}$?

Answer 1

Hint: We will attempt this question by finding out the atomic number and number of electrons in a Krypton (Kr) atom followed by calculating the total number of electron in the given noble gas notation and then further find out the element with the respective configuration.

Complete answer:
Let’s first discuss about electronic configuration:-
-It is known to us that electron configuration of an element describes how electrons are distributed in its atomic orbitals. This configuration follows a standard notation where all atomic sub shells containing electrons (here the number of electrons they hold are written in superscript) are placed in a sequence.
-The standard notation seems to be lengthy electron configurations (mostly in case of elements that have relatively large atomic numbers). In such cases, an abbreviated notation can be used by us instead of the standard notation in which the sequence of completely filled subshells that 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$[Kr]5{{s}^{1}}$, so let us first calculate the number of electrons in Krypton atom:-
The atomic number of Krypton is = 36
Since the atomic number of an atom is equal to the number of protons as well as number of electrons in that neutral atom.
Therefore number of electrons in Krypton (Kr) = 36
-So the total number of electrons in $[Kr]5{{s}^{1}}$ = 36 +1 = 37
Since the number of electrons is 37 which means the atomic number of the element will also be 37 and rubidium is the element whose atomic number is 56.
-Hence, Rubidium is represented as $[Kr]5{{s}^{1}}$?.

Note:
The standard electronic configuration for Rubidium is: $1{{s}^{2}}2{{s}^{2}}2{{p}^{6}}3{{s}^{2}}3{{p}^{6}}3{{d}^{10}}4{{s}^{2}}4{{p}^{6}}5{{s}^{1}}$which is an alkali metal and has a +1 valency. Here $1{{s}^{2}}2{{s}^{2}}2{{p}^{6}}3{{s}^{2}}3{{p}^{6}}3{{d}^{10}}4{{s}^{2}}4{{p}^{6}}$is the electronic configuration for Krypton (Kr).
-Kindly learn the periodic table along with the atomic number of elements, especially noble gas elements for solving such types of questions.