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Grade 11Physical Chemistry

An element crystallizes in fcc lattice having edge length 400 pm. Calculate the maximum diameter of atom which can be placed in interstitial site without distorting the structure.

Profile image of Simran Bhatia
12 Years agoGrade 11
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2 Answers

Profile image of Sakshi
11 Years ago
For an fcc, if one says that the \sqrt{2 } a = 4r

thus, r = a/2 \sqrt{2 }
Thus, the maximum diameter of the atom to be occupied in the interstitial site is a/ \sqrt{2 }
Profile image of Yeshwanth Talwar
9 Years ago
Either octahedral voids –r 0.414r ⎛ ⎞ ⎜ ⎟ ⎝ ⎠ or tetrahedral voids –r 0.225r ⎛ ⎞ ⎜ ⎟ ⎝ ⎠ are occupied by interstitial sites inFCC where r+ is the radius of atom in interstitial sites and r– is the radius of atom forming the cubic lattice.Diameter of interstitial site = 117.1 = 2 0.414 24 a a = 400 pm