This document discusses atomic radius and van der Waals radius. It defines atomic radius as the distance from the nucleus to the outermost electron and van der Waals radius as half the distance between two unbonded atoms when their electron shells interact. It then provides a periodic table showing van der Waals radii in picometers for each element, with trends of increasing and decreasing radii across periods and down groups.

1. Atomic Radius (van der Waal’s radius)
Dr. Mithil Fal Desai
Shree Mallikarjun and Shri Chetan
Manju Desai College Canacona Goa

2. Atomic radius
r
Radius = distance of valance electron of
outermost orbit to the centre of the atom
How do we
measure?
e-

3. Vander Waal’s force
Distance
Energy
2r

4. van der Waal’s radius
2r
van der Waal’s radius of element is half the
inter-nuclear distance when the valance shells of
the two atoms are in not bonded together.
r r

5. Periodic trend
H
120-
145
He
180
Li
180
Be B
C
165-
170
N
155
O
150
F
150-
160
Ne
160
Na
130
Mg
Al Si P S Cl
Ar
190
K
280
Ca Sc Ti V Cr Mn Fe Co
Ni
160
Cu
140
Zn
140
Ga
190
Ge As
Se
190
Br
180-
200
Kr
200
Rb
Sr
Y Zr Nb Mo Tc Ru Rh
Pd
160
Ag
170
Cd
160
In
190
Sn
220
Sb Te I Xe
Cs Ba La Hf Ta W Re Os Ir
Pt
170-
180
Au
170
Hg
150
Tl
200
Pb
200
Bi Po At Rn
Fr Ra Ac Rf Db Sg Bh Hs Mt Ds Rg
Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu
Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No Lr
van der Waal radii in pm
Increases
Decreases