<P> In some cases the anions take on a simple cubic packing, and the resulting common structures observed are: </P> <Table> Common ionic compound structures with simple cubic packed anions <Tr> <Th> Stoichiometry </Th> <Th> Cation: anion coordination </Th> <Th> Interstitial sites occupied </Th> <Th_colspan="3"> Example structure </Th> </Tr> <Tr> <Th> </Th> <Th> </Th> <Th> </Th> <Th> name </Th> <Th> critical radius ratio </Th> <Th> Madelung constant </Th> </Tr> <Tr> <Td> MX </Td> <Td> 8: 8 </Td> <Td> entirely filled </Td> <Td> cesium chloride </Td> <Td> 0.7321 </Td> <Td> 1.762675 </Td> </Tr> <Tr> <Td> MX </Td> <Td> 8: 4 </Td> <Td> half filled </Td> <Td> calcium fluoride </Td> <Td> </Td> <Td> </Td> </Tr> <Tr> <Td> M X </Td> <Td> 4: 8 </Td> <Td> half filled </Td> <Td> lithium oxide </Td> <Td> </Td> <Td> </Td> </Tr> </Table> <Tr> <Th> Stoichiometry </Th> <Th> Cation: anion coordination </Th> <Th> Interstitial sites occupied </Th> <Th_colspan="3"> Example structure </Th> </Tr> <Tr> <Th> </Th> <Th> </Th> <Th> </Th> <Th> name </Th> <Th> critical radius ratio </Th> <Th> Madelung constant </Th> </Tr>

Describe the structure of ionic solids such as nacl