Estimate the averaage atomic mass density of a sodium atom, assuming its size ot be 2.5 Å. Compare it with density of sodium in its crystalline phase `(970 kg m^(-3))`. Are the two denities of the same order of magnitude ? If so, why ?

Explanation

Atomic volume ` = (4)/(3) pi R^3xxN = (4)/(3)xx(22)/(7) (1.25xx10^(10))^3 xx6.023xx10^(23)m^3 = 4.93xx10^(-6)m^3`
Avarge mass density = `("mass")/("volume") = (23xx10^(-3))/(4.93xx10^(-6)) = 4.67xx10^3 kg//m^3`
The two densites are not of the same order. This is due to interatomic spacing in the crystalline phase.