Page 2 - LN 4
P. 2
So for homonuclear diatomic molecule,
r covalent = ½ [internuclear distance between two bonded atoms]
r covalent = ½ [ bond length]
For example :
Covalent radius of hydrogen is 37 pm.
Covalent radius of chlorine is 99 pm.
(2) van der Waal Radius:
It is defined as one-half the distance between
the nuclei of two adjacent identical atoms belonging to two
neighbouring molecules of an element in the solid state.
For example :
The van der Waal radius of hydrogen is 120 pm.
The van der Waal radius of hydrogen is 180 pm.
Metallic radius :
It is defined as one-half the inter-nuclear distance between two
adjacent metal ions in the metallic lattice.
Example :
Metallic radius of Na = 154 pm
Metallic radius of K = 231 pm
Metallic radius of Cu = 128 pm
Comparision :
van der Waal radius > metallic radius >co valent radius.
Variation of atomic radii in a peroid :
