In modeling solid state structures atoms and ions are

This preview shows page 2 - 4 out of 9 pages.

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 face centered cubic structure that is 3.71 on each side, answer questions (a)-(e). (1 = 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 3 ? 3
(c) Assuming that the atoms are spheres and the radius of each sphere is 1.31 , what is the volume of one atom in 3 ? ( V sphere = 4/3 π r 3 .) 3
(d) Therefore, what volume of atoms are in one unit cell? 3
(e) Based on your results from parts (b) and (d), what is the packing efficiency of the solid expressed as a percentage? %
Additional Materials
3. 5/5 points | Previous Answers NCSUGenChem102LabV1 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, iron has a density of 7.87 g/cm 3 and a unit cell side length a of 2.87 = 1. 10 -8 cm.) (a) How many iron atoms are in exactly 1 cm 3 . (1 ?
(b) How many unit cells are in exactly 1 cm 3 ?
11/25/14, 12:38 PM Lab 6 PostLab - Solid State Modeling
Page 3 of 9 (c) How many iron atoms are there per unit cell?

  • Left Quote Icon

    Student Picture

  • Left Quote Icon

    Student Picture

  • Left Quote Icon

    Student Picture