Question

what is vanderwaal's radius ?

Answer 1

The van der Waals radius of an atom is the radius of an imaginary hard sphere which can be used to model the atom for many purposes.
\[V=4/3πr ^{3}\]

Answer 2

it is the largest radius but does not give the accurate radius it always show bigger then actual it is...because it is measured from the centre of both the elements and when divided from the middle of radius it dosent touch the periphery....look at the diagram
here the spaces between the elements are also calculated in the radius