Final answer:
The length of an edge of the unit cell when barium (atomic radius 222 pm) crystallizes in a body-centered cubic (bcc) unit cell is 888 pm.
Step-by-step explanation:
Barium crystallizes in a body-centered cubic (bcc) unit cell, which means that there is an atom at each corner of the cube and one atom in the center of the cube.
The edge length of a bcc unit cell can be found using the formula:
Edge length (a) = 4 * (Radius of the atom)
In this case, the atomic radius of barium is given as 222 pm. So, the edge length of the unit cell is:
Edge length (a) = 4 * (222 pm) = 888 pm
Therefore, the length of an edge of the unit cell when barium crystallizes in a bcc unit cell is 888 pm.