Magnesium has the hexagonal close– packed crystal structure. The lattice parameters for magnesium are a = 0.32087 nm and c = 0.5209 nm, and the atomic radius is 0.1604 nm

(a) What is the number of atoms per unit cell in the hexagonal close–packed structure?

(b) Determine the atomic packing factor of the Mg unit cell.

(c) Is the c/a ratio for Mg greater than or less than the ideal HCP c/a ratio?

Will slip be harder or easier in Mg compared to the ideal HCP structure? Explain your answer fully.