Sodium metal crystallises in body centred cubic lattic with the cell edge, 4.29 Å . What is the radius of radius of sodium atom ? What is the length of the body dioganl of the unit cell ?

Explanation

For body centred cubic lattic, the relationship between the cell edge (a) and the radius of the atom is
` r= sqrt3/4 a = 1.732/4 xx 4.29 = 1.86 Å`
Length of body diagonal = 4 r = ` 4 xx 1.86 Å = 7.44 Å`