If a salt has a face-centered cubic (fcc) unit cell and a 1:2 cation:anion stoichiometry with cations occupying the fcc positions, then the anions fill all the ________ holes.
A) cubic
B) octahedral
C) tetrahedral
D) octahedral and tetrahedral
E) cubic, octahedral, and tetrahedral

Question

Quizplus · Accepted Answer

In a fcc unit cell, there are 4 tetrahedral holes and 2 octahedral holes. Since a 1:2 cation:anion stoichiometry is stated and cations occupy the fcc positions, the anions must fill all the tetrahedral holes.

If a Salt Has a Face-Centered Cubic (Fcc) Unit Cell