Question

Study the variation in the atomic radii of elements given below and arrange
them in increasing order :
Na Li Rb Cs K
186 152 246 262 231
(a) Name the element which has the smallest and the largest atomic size.
(b) How does the atomic size vary as we go down a group ?

Answer 1

Given :
Atomic radii of elements :

Na Li Rb Cs K
186 152 246 262 231

Increasing order :
Li     Na          K      Rb      Cs
152  186         231  246      262    

Smallest Atomic Radii ---Lithium
Largest Atomic radii -- Cesium

As we move down in a group, atomic radius increases.

Answer 2

hey mate !!!

a) Lithium have smallest atomic size.

it have a smallest atomic size because there is 3 electron present so that the attraction of nucleus with electron is more due to presence of proton.

largest atomic size is =>Cs.

b) as we move down towards the periodic table we find that the atomic size is increases.

as we move down from periodic table to up we find that atomic size decreases

this variation occur due to adding of electron or losing of electron.

for example if We moved downward than the electron added and atomic size increases.

but if you move from downward to upward electron decreases and atomic size decreases.

hope it helps!!!
thanks