Write a note on
(a) Atomic radius.

Explanation

Crystal Radius (Atomic radius or Metallic radius): The term is used for metal atoms. A metallic crystal contains metal atoms in close packing. These metal atoms are considered spherical. They are supposed to touch each other in the crystal. The crystal radius is half the internuclear distance between two adjacent atoms. e.g.: The internuclear distance between two adjacent sodium atoms in a crystal of sodium metal is `3.72 Å`. So crystal radius of sodium is `(3.72)/(2)= 1.86Å` For potassium it is `2.31 Å`