Question

A element with largest atomic size from period 1,2,3

Answer 1

Lithium

Sodium

Potassium

Answer 2

The largest atomic size in

Period 1 is Hydrogen

Period 2 is Lithium

Period 3 is Sodium

Period 4 is Potassium

Because the have only one electron in the Shell as the electron number increases the electrons are attracted towards the nucleus which make their atomic size smaller than the metals in alkali metals group 1. I hope this helped in solving your problem.