Question

how does the atomic radius of the elements change (a)from left to right in periodic(b)down a group in modern periodic table?give reasons

Answer 1

Hey dear here is your answer,

a)From left to right atomic radius decreases

b)From top to bottom atomic radius increases

When it moves from left to right the number of electrons in the valence shell

increases so the force of attraction increases so the radius decreases.

When it moves from top to bottom the shell increases so the radius increases

hope it helped you

Answer 2

a) When we move from left to right in a period the atomic radius decreases as there is consecutive addition of one proton in the nucleus and one electron in the valence shell. It increases the positive charge which consequently pulls the extra nuclear electrons in the outermost shell inwards.
b) down the group the atomic radius increases because of the addition of extra shell of electrons.
Hope it is helpful.