Question

If size increase down the group then why there is maximum difference of atomic size between Na&K​

Answer 1

Answer:

as an example,potassium(k)has a larger average atomic radius(220 pm) then sodium(na)does(180 pm).the potassium atom has an extra electron shell compared to the sodium atom,which means it's valence electrons are further from the nucleus,giving potassium a larger atomic radius.