Question

How does the atomic radius change as we go :

(i) from left to right across a period

(ii) down a group in the periodic table ?

Answer 1

On going:

(i) From left to right across a period, atomic radius decreases as one proton and one electron are added continuously, therefore effective nuclear charge increases.

(ii) down a group in the periodic table, atomic radius increases because the number of shells goes on increasing, therefore, the distance between nucleus and valence shell increases