# Quiz 08 crystal structures part 2 mat e 273

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Quiz 08 - Crystal Structures - Part 2: Mat E 273 Answer 1: Answer 2: {111} Note: All this question really asks is: What crystallographic planes within FCC are close-packed? This answer is the same for any identical sized spheres that pack in an FCC arrangement, regardless of whether they are atoms (like metals) or molecules (like C ). 60 London forces Correct! Correct! Correct! Correct!
6/11 5 / 5 pts Question 4
12/6/2018 Quiz 08 - Crystal Structures - Part 2: Mat E 273 Which of the following cubic crystal structures offer an atomic packing factor (APF) of 0.74, the theoretical maximum for equal- sized spheres in 3D? Select all that apply. Correct! Correct!
7/11 5 / 5 pts Question 6
DC HCP 3 / 3 pts Question 5 Compute the density of the fictional metal Vibranium, if its atomic weight is 182 g/mol, its atomic radius is 2.2 angstroms, and the metal packs with a BCC structure. Correct! Correct! Correct Answers Correct Answers
12/6/2018 Quiz 08 - Crystal Structures - Part 2: Mat E 273 8/11 Certain crystal structures are sometimes similar to other crystal structures in a variety of ways. This problem demonstrates one of the similarities that exists between two of the crystal structures we've discussed so far. Specifically, a crystallographic family of planes in one of these structures is equivalent to a crystallographic family of planes in the other structure (provided the atoms in each structure are the same ... aka we're just talking about one element here). So, in general, equivalent planes within various crystal structures of the same element feature identical 2D packing schemes, but these equivalent planes do not necessarily feature the same plane designation {hkl}. The figure below depicts a plane of atoms of radius R in some crystal. The plane intersects the atoms through their centers. Therefore, we do not see atoms above and below this plane. We just see the circular cross-sections of the atoms that lie within the plane.
12/6/2018 Quiz 08 - Crystal Structures - Part 2: Mat E 273