Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Coordination number for fcc and NaCl

  1. May 4, 2014 #1
    Why is the coordination number for fcc 12, but that in NaCl 6? NaCl crystallises in ccp (or fcc) lattice, then how is it possible?
  2. jcsd
  3. May 4, 2014 #2
    I'm sorry you are not generating any responses at the moment. Is there any additional information you can share with us? Any new findings?
  4. May 5, 2014 #3


    User Avatar
    Science Advisor

    You have to differentiate between the lattice and the crystal structure. Some metals crystallize in a fcc lattice with a primitive basis, i.e. there is only one atom in the primitive cell. Then you can show that each of this metal atoms is coordinated by 12 other atoms. In NaCl, there are two atoms per primitive cell and this changes the situation. It is still true that e.g. each Na has 12 nearest Na ions in that lattice.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook