Question

How do atomic radius vary in the periods and Groups how do you explain the variations

Answer 1

Answer:

atomic radius increases going down the period and decreases while along the group

Explanation:

Answer 2

Answer:

Atomic radius declines as we move from left to right in a period. It happens because in a period, the external electrons are available in a similar valence shell so, the atomic number increments from left to right in a period, which results in increase in the effective nuclear charge. Therefore, the attraction of electrons towards the nucleus is increased.

Also, atomic radius declines as we move from top to bottom in the group. It happens because as we move down in a group then there is increase in  principal quantum number(n) which brings about increase in the  distance between nucleus and the valence electrons.