0.7 Solid state and superconductors  (Page 4/9)

·Use the guide at left and place four colorless spheres in the first layer (1) at the corners for z=0.

·Place one colorless sphere in the second layer (2) on the center rod for z=0.5

·Construct the z=1 layer.

 Group 2.Extended Structure

• Using template F, construct an extended body-centered cubic structure.
• Insert rods in every hole of the template/block.
• Using the guide which follows, place colorless spheres for z=0 on every rod labeled 1.
• For z=0.5 place colorless spheres on each rod labeled 2.
• Complete the z=1 layer and then place another two layers on top.

• Face-Centered Cubic (FCC) Structure

Team C

Group 1. Single Unit Cell

·Construct a single face-centered cubic cell using template C, colorless spheres and the layering as illustrated. Only put rods and spheres on one of the squares defined by the internal lines.

Group 2. Extended Structure

·Construct an extended face-centered cubic structure using template C (You can find instructions on how to do it in the manual that comes with the kit.)

3. Close-Packing: Sphere Packing&Metallic Elements

Team D

Group 1. Construct the hexagonal close-packing unit cell (use the one requiring the C6 template)

Group 2. Construct the cubic close-packing unit cell (use the one requiring the C6 template)

Team E

Group 1. Add a 2' layer on top of the existing structure.

Group 2. Add a 2' layer on top of the existing structure.

Team F

Using only the shaded portion on the template, construct the face-centered cubic unit cell which uses the C4 template.

Compare the structures of the face-centered cubic unit cell made on the C4 template to that made on the C6 template.

4. interstitial sites and coordination number (cn)

Team a

Group 1 - Construct CN 8, CN 6 and CN 4 (using the C4 template).

Group 2 - Construct CN 6, CN 4 (body diagonal) (using the C6 template).

5. ionic compounds

Now we will look at some real ionic compounds which crystallize in different cubic unit cells. We will use the models to determine the stoichiometry ( atom-to-atom ratios) for a formula unit.

Team B

Cesium Chloride

·Construct a model of cesium chloride on template A. This time use colorless spheres as layers 1 and 1' and the green spheres for layer 2.

·Start with the shaded area and then work your way outward to an extended structure. Consider both simple and extended structures when answering the questions which follow.

Team c

Fluorite: calcium fluoride

·Construct a model of fluorite, which is calcium fluoride, on template E.

·Green spheres will be used for layers 1, 3, and 1' while colorless spheres go on layers 2 and 4.

·Finish with a 1' layer on top. Build the structure by placing rods in all 13 holes in the area enclosed by the internal line.

Team d

Lithium nitride

·Use the l template and insert 6 rods in the parallelogram portion of the dotted lines.

·Construct the pattern shown below. be sure to include a z=1 layer. 1 is a green sphere while 1 and 2 are blue spheres. The 0 Indicates a 4.0 mm spacer tube; the 2 Is an 18.6 mm spacer.

Teams e and f

Zinc blende and wurtzite: zinc sulfide

Team E. Zinc Blende: Use template D to construct the crystal pattern illustrated below. Numbers 2 and 4 are blue spheres while 1 and 3 are colorless spheres and 4 is a 16.1 mm spacer.