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Problem: The unit cells for cesium chloride and barium chloride are shown. Identify the structure of each of the two unit cells shown below as the rock salt structure, zinc blende structure, fluorite structure, antifluorite structure, or none of these.

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We are being asked to determine the crystal structure for the given unit cells.

The figure shows 2 unit cells: one for cesium chloride and the other for barium chloride. Cesium chloride unit cell has chlorine atoms in the corners of the cube and a cesium atom in the center of the cube. Barium chloride unit cell has barium atoms at the corners of the cube and also in the center of each face of the cube. There are 8 chlorine atoms as well: each of them is connected to 1 barium atom in the corner and 3 barium atoms in the faces.


We are to choose from a rock salt structurezinc blende structurefluorite structureanti-fluorite structure or none of these.


Recall: Crystalline solids represent structures with well-organized patterns and shapes


Rock salt structure can be visualized as anions occupying the lattice sites of a face-centered cubic structure with the smaller cations occupying the holes between the anions.

 It has a cation to anion ratio of 1:1. An example is the structure of NaCl shown below.


Zinc blende structure can be visualized as anions occupying the lattice sites of a face-centered cubic structure with the smaller cations occupying four of the eight tetrahedral holes located directly beneath each corner atom

It has a cation to anion ratio of 1:1. An example is the structure of ZnS shown below.

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Problem Details
The unit cells for cesium chloride and barium chloride are shown. Identify the structure of each of the two unit cells shown below as the rock salt structure, zinc blende structure, fluorite structure, antifluorite structure, or none of these.

The figure shows 2 unit cells: one for cesium chloride and the other for barium chloride. Cesium chloride unit cell has chlorine atoms in the corners of the cube and a cesium atom in the center of the cube. Barium chloride unit cell has barium atoms at the corners of the cube and also in the center of each face of the cube. There are 8 chlorine atoms as well: each of them is connected to 1 barium atom in the corner and 3 barium atoms in the faces.

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What scientific concept do you need to know in order to solve this problem?

Our tutors have indicated that to solve this problem you will need to apply the Unit Cell concept. You can view video lessons to learn Unit Cell. Or if you need more Unit Cell practice, you can also practice Unit Cell practice problems.

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Based on our data, we think this problem is relevant for Professor Timkovich's class at UA.