The crystal structures of many binary ionic compounds of the type AB, AB2 and A2B are related in a simple manner tho the close packed arrangements. Verify often, ionic compounds list. The larger atoms form the close packed structure, and the smaller atoms occupy the voids between the close packed structures. Ionic compounds list.
Examples of ionic compounds, if an atom B is larger than the atom A, then the B atoms will form the close packed structure and A atoms will occupy the voids. Then,
1} The compound AB corresponds to a structure in which B atoms form the close packed structure and filling half of the tetrahedral holes or voids, or the octahedral holes by the atoms A.
2} for a compound of the type A2B, then B atoms form the close packed structure and all tetrahedral holes are occupied by A atoms. Examples of ionic compounds.
List of ionic compounds:
Ionic compounds occur in crystalline forms. Ionic crystals are made of cations and anions. These ions are arrangement three dimensional array to form an aggregate of the type (A+B-)n. Since, ionic compound examples the coulomb forces are non – directional, hence the structures of such crystals are mainly governed by the ratio of the radius of cation r+ to that of anion r-. The ratio, r+/r- is called as Radius Ratio.
The description of the ionic solids forming nearly close packed structures are summarized and discussed below:
1}The compound NaCl has 95 radius of cation and 181 radius of anion. The ratio of radius is 0.525 and the coordination number of cation and anion is 6:6. The structure forming ion of NaCl compound is cl- (ccp). In this compound all octahedral voids are occupied by Na+ ions. Examples of ionic compound.
ZnS has 74 radius of cation and 184 radius of anion. The ratio of radius is 0.402 and the coordination number of cation and anion is 4:4. The structure forming ion of ZnS compound is S2- (ccp). In this compound all alternate tetrahedral voids are occupied by Zn2+ ions.