Structures of Ionic Solids

The structures of a wide rage of ionic solids can be systematically described as being derived from set of closest-packed anions with the cations located in some fraction of the tetrahedral and octahedral holes formed by the lattice. The table below summarizes the structures of some of the more common ionic solids and classifies them according to the packing of the anions and the fraction of tetrahedral and/or octahedral holes filled.

For each structure listed, clicking on the structure name will link you to the MAGE computer file containing that particular structure. This requires that you have the Mage Software and that your WWW browser is configured to work with the MAGE program.

structure	example formula	close packing	fraction of tetrahedral holes filled	fraction of octahedral holes filled
antifluorite	K₂O	ccp	1	0
sphalerite	ZnS	ccp	1/2	0
wurtzite	ZnS	hcp	1/2	0
rock salt	NaCl	ccp	0	1
nickel arsenide	NiAs	hcp	0	1
cadmium chloride	CdCl₂	ccp	0	1/2 (layered)
cadmium iodide	CdI₂	hcp	0	1/2 (layered)
alumina	Al₂O₃	hcp	0	2/3
spinel	MgAl₂O₄	ccp	1/8 (Mg)	1/2 (Al)

For more information:

There are several MAGE tutorial files available designed specifically to address subjects such as closest packing and tetrahedral and octahedral holes.

Questions? Send all inquiries to Dean H. Johnston, Otterbein College Chemistry Department Last updated 6/6/97