# In modeling solid state structures atoms and ions are

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In modeling solid-state structures, atoms and ions are most often modeled as spheres. A structure built using spheres will have some empty, or void, space in it. A measure of void space in a particular structure is the packing efficiency , defined as the volume occupied by the spheres divided by the total volume of the structure. Given that a solid crystallizes in a body centered cubic structure that is 3.65 Å on each side, answer questions (a)-(e). (1 Å = 1. 10 -10 m.) (a) How many total atoms are there in each unit cell?
(b) What is the volume of one unit cell in Å 3 ?
(c) Assuming that the atoms are spheres and the radius of each sphere is 1.58 Å , what is the volume of one atom in Å 3 ? ( V sphere = 4/3 π r 3 .)
(d) Therefore, what volume of atoms are in one unit cell?
(e) Based on your results from parts (b) and (d), what is the packing efficiency of the solid expressed as a percentage? (No Response) 68.0 % Additional Materials Solid State Modeling
3/13/2018 Lab 6 PostLab - Solid State Modeling 3. –/5 pointsNCSUGenChem102LabV1 6.POST.03. Many metals pack in cubic unit cells. The density of a metal and length of the unit cell can be used to determine the type for packing. For example, platinum has a density of 21.45 g/cm 3 and a unit cell side length a of 3.93 Å . (1 Å = 1. 10 -8 (a) How many platinum atoms are in exactly 1 cm 3 cm.) ?
3/9 (b) How many unit cells are in exactly 1 cm 3 ?
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