A hypothetical metal has a simple cubic crystal structure. If its atomic weight is 70.6

Question

g/mole and the atomic radius is 0.128 nm, compute its density.

Answer 1

In a simple cubic crystal there is 1 atom/unit cell so the mass of 1 atom is
70.6 g/mol/6.022E23 atoms/mol= 1.172E-22 g/atom
In the crystal a = 2r = 2*0.128E-9 nm = 2*1.28E-8 cm = 2.56E-8 cm
Volume of 1 atom = a^3 = (2.56E-8 cm)^3 = 1.68E-23 cc
density = mass/volume = 1.172E-22/1.68E-23 = 6.98 g/cc