InterviewSolution
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InterviewSolution
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In calcium fluoride `(CaF_(2))`, the coordinate number of each `Ca^(2+)` ion is `"_______"` and that of each `F^(-)` ion is `"______"`.A. `8,4`B. `4,8`C. `4,4`D. `8,8` |
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Answer» Correct Answer - 2 In `CaF_(2)` (fluorite) structure,the `Ca^(2+)` ions are located at the face centred cubic lattice points and ,therfore ,have cubic closet packed arrangement ,The fluroide ions `(F^(-)`ions) occupy all the eight tetrahedral voids.Thus there are four `Ca^(2+)` ions and eight `F^(-)` ions in the unit cell of calcium fluoride. since `F^(-)` ion is present in the tetrahedral void ,it is surrounded by four `Ca^(2+)` ions.if we imagine that the unit cell is divided into eight subcubes then each `Ca^(2+)` ion sitting at the face centre is shared by eight minicubes ,Since the centre of each subcube is captured by `F^(-)` ions we can say that each `Ca^(2+)` ions is surrounded by `8F^(-)` ions. |
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