Find the coordination of `Na^(o+)` in `Na_(2)O`.

Answer

4

Explanation

`Na_(2)O` has antifluorite structure. `O^(2-)` ions constitute `c.c.p.` lattice while `Na^(+)` ions occupy the tetrahedral voids. Each `O^(2-)` ions is in contact with `8Na^(+)` ions and each `Na^(+)` ions is nin contance with `4O^(2-)` ions . Thus the co`-` ordination number of sodium in `Na_(2)O` is 4.