What can be learned from a crystal structure

To assess what can be learned from a crystal structure determination the results of a few selected structure analyses will now be analyzed in terms of the molecular geometry and packing in the crystal. 

The crystal structures of the chemical elements provide a simple starting point for illustrating what can be learned from listed atomic coordinates. Tin has both a nonmetallic and a metallic allotrope (polymorph). 

In crystals of white tin the tin atoms are located in the unit cell at  

Earth tin atom has six nearest neighbors. Four tin atoms lie 3.023 A from one selected tin atom, and two tin atoms lie 3.182 A (one unit celi dimension c) from it. 

both the coordination number and the Sn Sn distances are decreased in the low-temperature form which is isostructural with diamond. 

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