Posted by
**Stephanie** on
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The atoms in barium metal are arranged in a body centered cubic unit cell. Calculate the radius of a barium atom in A if the density of barium is 3.50g/cm3. The atomic weight of barium is 137.34.

The atoms in barium metal are arranged in a body centered cubic unit cell. Calculate the radius of a barium atom in A if the density of barium is 3.50g/cm3. 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 (2 x 137.34)/6.023 x 10^23 = ??g.
vol = mass/d = ??g/3.50 g/cc = xx cc.
The edge length of a cube then is the cube root of xx cc or
(xx cc)**

^{1/3}= a The body diagonal is 4 x the radius and equals a*1.732; therefore r = (a*1.732)/4. Just for a check, I obtained 2.20 A. My periodic table lists 1.98 A. Check my thinking. Check my arithmetic.