Question

'In a group, the atomic radii increase with increasing period number', explain this statement and justify it with reference to group 17.

Answer 1

Increase in periodic number means increase in the number of shells in atoms. For example, in group 17, the number of shells increases on descending down the group from fluorine to iodine. So, an extra shell is added to the atom after each period which increases the size of the atom. Therefore, atomic radii increases with increase in period number.