Chemistry 124 Fall 2006SOLID STATE MODELING EXPERIMENT page 1

NAMES
Chemistry 124 Fall 2006

SOLID STATE STRUCTURES

Cubic Unit Cells

Project 1: Simple Cubic (SC) Unit Cells

1-1 z - diagram(s) / 1-2 stacking pattern
(3D illustration of unit cell)
1-3 number of corner spheres / 1-4 / contribution of a corner atom to the unit cell
1-5 net number of atoms per unit cell / 1-6 / coordination number of each corner sphere
1-7 length of one side of the unit cell
1-8 % packing efficiency (show calculations and geometric diagrams)
1-9 Find an element which crystallizes in this type of unit cell.
source of information:

Project 2: Body-Centered Cubic (BCC) Unit Cells

2-1 z - diagram(s) / 2-2 stacking pattern
(3D illustration of unit cell)
2-3 volume of the cube generated using the radius,r, of the atoms
(show calculations)
2-4 number of corner spheres / 2-5 / contribution of a corner atom to the unit cell
2-6 contribution of a center sphere to a unit cell / 2-7 / net number of atoms per
unit cell
2-8 coordination number of each center sphere / 2-9 / coordination number of each corner sphere
2-10 % packing efficiency (show calculations and geometric diagrams)
2-11 Find an element which crystallizes in this type of unit cell.
source of information:

Project 3: Face-Centered Cubic (FCC) Unit Cells

3-1 z - diagram(s) / 3-2 stacking pattern
(3D illustration of unit cell)
3-3 volume of the cube generated using the radius,r, of the atoms
(show calculations)
3-4 number of corner spheres / 3-5 / contribution of a corner atom to the unit cell
3-6 number of face spheres / 3-7 / contribution of a face atom to a single unit cell
3-8 / net number of atoms per
unit cell
3-9 coordination number of each face sphere / 3-10 / coordination number of each corner sphere
3-12 % packing efficiency (show calculations and geometric diagrams)
3-13 Find an element which crystallizes in this type of unit cell.
source of information:

Stoichiometry

Project 4: Cesium Chloride

4.1 z-diagram(s) (be sure to distinguish different colors & atoms)
4.2 Type of cubic cell generated only by the colorless spheres / 4.3 Type of cubic cell generated only by the green spheres
4.4 Green sphere represents which element? / 4.5 Colorless sphere represents which element?
4.6 Stoichiometry (formula) for cesium chloride.
4.7 Explain how this formula corresponds to what might be predicted by the Periodic Table.

Project 5: Calcium Fluoride (fluorite)

5.1 z-diagram(s) (be sure to distinguish different colors & atoms)
5.2 Type of cubic cell generated only by the colorless spheres / 5.3 Type of cubic cell generated only by the green spheres
5.4 Green sphere represents which element? / 5.5 Colorless sphere represents which element?
5.6 Stoichiometry (formula) for calcium fluoride.
5.7 Explain how this formula corresponds to what might be predicted by the Periodic Table.

Project 6: Lithium Nitride

6.1 z-diagram(s) (be sure to distinguish different colors & atoms)
6.2 What is the stoichiometry of blue to green spheres? / 6.3 To which type of cubic cell might this be related?
6.4 Green sphere represents which element? / 6.5 Blue sphere represents which element?
6.6 Stoichiometry (formula) for lithium nitride.
6.7 Explain how this formula corresponds to what might be predicted by the Periodic Table.

Project 7: Zinc Blende (Zinc sulfide)

7.1 z-diagram(s) (be sure to distinguish different colors & atoms)
7.2 What is the stoichiometry of blue to colorless spheres? / 7.3 To which type of cubic cell might this be related?
7.4 Blue sphere represents which element? / 7.5 Colorless sphere represents which element?
7.6 Stoichiometry (formula) for zinc sulfide.
7.7 Explain how this formula corresponds to what might be predicted by the Periodic Table.
Discussion Questions

1. What are the relative edge lengths of the sc, bcc, and fcc structures?

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Briefly explain your order.

2. Consider the following z diagram for crystal structures. Determine the simplest formula for this compound.

What are the contributions of each atom to each layer in the unit cell?

The overall simplest formula which can exist is

3. Shown below is the z-diagram structure for thallium fluoride, TlxFy. The darker circle represents thallium and the lighter one fluoride. What is the simplest formula which can exist for thallium fluoride? Briefly justify your answer.

4. Draw the z-diagrams for the unit cell structures of sodium chloride and then of Cu3Au. Cu3Au alloy can be described as a simple cubic arrangement of gold atoms with copper atoms occupying face centered positions. (Look up NaCl structure…)

Sodium chloride – z-diagrams / Cu3Au – z-diagrams

Discussion

**Briefly discuss two concepts which are now clearer to you because of the solid state modeling exercises.