Li is larger than that of Be . Why?

Question

Li is larger than that of Be . Why?

Answer 1

Li has lesser effective nuclear charge than that of  Be and so it is larger than  Be.  

Answer 2

Beryllium's nucleus has a stronger effective nuclear charge and that will pull the valences electrons closer, therefore decreasing radius.

Answer 3

very good question,

if you look at a periodic table, as you look down a vertical column (group) you will see that the size of atoms increase in size. that's because there is an additional shell added for each row it moves down.

but if you look across each row, you will the size of atom decreasing. in you case, it is Be being smaller than Li.

note: every element in the same row have the same number of shells.

this is because there are more and more protons. their positive charge attracts the negative electrons. the more electrons and protons, the bigger the attraction, and the size of the atom gradually decreases

this website will explain it better;

http://en.wikipedia.org/wiki/Atomic_radi...