Need help with lab report discussion. The link below is my lab. http://www.macal

Question

Need help with lab report discussion. The link below is my lab.

http://www.macalester.edu/~kuwata/Classes/2002-03/Chem%2056/Crystal%20Structures%20Lab.pdf

Im not at that college, but my lab is the exact same thing as them. However, I need help with the discussion part of my lab report. I did everything, now I am totally stuck on the discussion part. I have the definitions for the simple cubic unit cell, body centered cubic cell, face centered cubic cell, but I dont know how to put it all together. Please help

Explanation / Answer

In the discussion part we sum up what we have observed and learned. Generally, it is Results and discussion part.

Discussion

The experiment and calculations went on with no difficulties and errors. The use of model set was more than helpful. All the mentioned types of structures were observed and completely understood.

Radii and charge on the atoms play important role in deciding the crystal structure. Radii includes both ionic and atomic radius.

Simple cubic structure is the simplest form we can find. In SC number of ions or atoms per unit cell is equal to one. Density and volume of unit cell was calculated by d0. In SC each atom is connected to six others therefore coordination number is 6.

Body centered cubic structure (BCC) is the more complex form. Coordination number is 8. In BCC space between the corner atoms is filled with atom of same kind.

Face centered cubic crystals (FCC) contains atoms in the corner and center of each face. Close packed structures are similar to these. Copper, Silver, Nickel and Calcium prefer this structure. Coordination number is 12.

More complex the crystal becomes coordination number increases. Also the fraction space occupied increase with complexity.

r+/r- value decides the crystal type. NaCl is FCC while CsCl is BCC because Cs+ ion is larger than Na+.

Avogadro number is used to calculate the mass of a cell. Which, in turn was be used to calculate density.

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