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Grade 11Physical Chemistry

Bravais showed that there are only 14 types of crystal lattices possible. But if we consider a unit cell of say NaCl or ZnS, they do not seem to fall under any of the 14 different types of lattices...so are they deviations from what bravais said?

Profile image of Satviki Pathak
11 Years agoGrade 11
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3 Answers

Profile image of Pankaj
11 Years ago
Hello Student,
It is actually not so, NaCl has face centred cubic structure while ZnS has Hexagonal crystal.
Profile image of Satviki Pathak
11 Years ago
But NaCl unit cell has a cation at the body centre and edge centres and anions at the corners and face centres...which type of Bravais lattice actually describes this arrangement???? 
Profile image of Pankaj
11 Years ago
There are 6 Cl surrounding the Na, and 6 Na around each Cl. NaCl is made up of fcc / ccp lattices. The Na's occupy the octahedral sites in the Cl sub lattice, and the Cl's occupy the octahedral sites in the Na sub lattice.