Question

Arrange the elements Li, Na, K, Rb as required

Increasing order of atomic radii

Answer 1

Step-1: Introduction

The atomic radius is the distance of the electron in the outer most from the atomic nucleus.

The atomic radii increases from top to bottom in a group and decreases from left to right in a period but is highest for a noble gas.

Step-2: Grouping of element

The elements Lithium ($\mathrm{Li}$), Sodium ($\mathrm{Na}$), Potassium ($\mathrm{K}$), Rubidium ($\mathrm{Rb}$) belongs to group 1.

Since the elements belong to same group, the atomic radii increases from Lithium ($\mathrm{Li}$) to Rubidium ($\mathrm{Rb}$). This is due to increase in atomic number and the number of energy shells of electrons.

Final answer

Therefore, the increasing order of atomic radii is Lithium ($\mathrm{Li}$), Sodium ($\mathrm{Na}$), Potassium ($\mathrm{K}$) and Rubidium ($\mathrm{Rb}$).