Question

Which of the four kinds of packing used by metals makes the most efficient use of space?

Choose all that apply:
A. Body-centered cubic
B. simple cubic
C. hexagonal closest-packed
D. cubic closest-packed

Answer 1

Hexagonal closest packing (HCP) and cubic closest packing (CCP) are the most efficient packing arrangements used by metals.

Step-by-step explanation:

The most efficient packing in metals is achieved through hexagonal closest packing (HCP) and cubic closest packing (CCP). In both HCP and CCP, the atoms are packed as compactly as possible with alternating layers. In HCP, the stacking consists of alternating close-packed layers in an ABABAB... pattern, whereas in CCP, the stacking consists of alternating close-packed layers in an ABCABCABC... pattern. About two-thirds of all metals crystallize in closest-packed arrays with coordination numbers of 12.