Final answer:
The key differences between face-centered cubic (FCC) and body-centered cubic (BCC) structures are the arrangement of atoms and the resultant density; FCC has atoms at corners and center of cube faces, making it denser, while BCC has a single atom at the center of the cube and is less dense.
Step-by-step explanation:
The main differences between a face-centered cubic structure (FCC) and a body-centered cubic structure (BCC) lie in their arrangement of atoms and density. In an FCC structure, atoms are located at each of the corners and the centers of all the faces of the cube, resulting in a total of 4 atoms per unit cell. This arrangement allows for tight packing and creates a denser structure compared to BCC. On the other hand, in a BCC structure, atoms are positioned at each corner of the cube, with a single atom at the center of the cube, giving a total of 2 atoms per unit cell. The BCC structure is less densely packed than FCC, making it less efficient in terms of space utilization. These structural differences result in distinct physical properties such as density and packing efficiency.