Question

Read below given tabular form and answer the questions.

Element	Electronic configuration
He	$1{{s}^{2}}$
Ne	$2{{s}^{2}}2{{p}^{6}}$
Ar	$3{{s}^{2}}3{{p}^{6}}$
Kr	$4{{s}^{2}}4{{p}^{6}}$
Xe	$5{{s}^{2}}5{{p}^{6}}$
Rn	$6{{s}^{2}}6{{p}^{6}}$

Write the name of the 5th period element?

Answer 1

Hint: The electronic configuration of the elements in the periodic table represents the atomic number of the element and also explains about position of the element in the groups and periods of the periodic table.

Complete Solution :
Radon.
- From the electronic configuration of the Helium, Neon, Argon, Krypton, Xenon and Radon we say that all the elements belong to VIII A group in the periodic table.
- In the question it is asked to find the element which belongs to the 5th period.
- The electronic configuration of the helium is $1{{s}^{2}}$ means helium belongs to the 1st period.
- The electronic configuration of the neon is $2{{s}^{2}}2{{p}^{6}}$ means neon belongs to the 2nd period.
- The electronic configuration of the argon is $3{{s}^{2}}3{{p}^{6}}$ means the argon belongs to the 3rd period.
- The electronic configuration of the krypton is $4{{s}^{2}}4{{p}^{6}}$ means the krypton belongs to the 4th period.
- The electronic configuration of the xenon is $5{{s}^{2}}5{{p}^{6}}$ means the xenon belongs to the 5th period.
- The electronic configuration of the radon is $6{{s}^{2}}6{{p}^{6}}$ means the radon belongs to the 6th period.
- Therefore the element which belongs to the 5th period among the given elements is Xenon.
- The name of the element belongs to the 5th period among the given elements Helium, Neon, Argon, Krypton, Xenon and Radon is Xenon.

Note: The electronic configuration of the elements gives so much valuable information about the chemical elements which are present in the periodic table. From the electronic configuration we can calculate the number of valence electrons present in an element also.