The fictional metal alloy Adamantium, from the Marvel Comics is often described as having a very high density, although descriptions are generally poor and inconsistent. so, we'll need to make some assumptions. Assuming it is a pure element. has a mass density equivalent to that of platinum 21.45g cm-3, has the hexagonal close packed crystal structure and has an atomic weight equal to that of lead (Pb), what is the atomic radius of Adamantium, m pm. One pm is 10-12 m. (Hint: what are the atomic packing factors of HCP and FCC?)