The atoms in barium metal are arranged in a bodycentered cubic unit cell. Calculate the radius of a barium atom if the density of barium is 3.50 g?cm23 . Hint: Use your answer to Exercise 4.18.

The radius of a barium atom is  r = 2.19   10^-8

Explanation:

The atomic weight of barium is 137.34.

The body-centered cubic structure has two atoms per unit cell.

Therefore, the mass of Ba in a unit cell is calculated as,

              volume = mass / density

               volume  =

The edge length of a cube then is the cube root of  or

The body diagonal is 4 x the radius and equals a  1.732,

Therefore       r = (a 1.732) / 4

                           = (5.06 10^-8

The radius of a barium atom is  cm.