\nThe face centred unit cell (FCC) contains atoms at all the corners of the crystal lattice and at the centre of all the faces of the cube. The atom present at the face centre is shared between adjacent unit cells and only of each atom belongs to an individual cell. The packing efficiency of FCC lattice is .
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Let be the radius of the sphere and be the edge length of the cube and the number of atoms or spheres is n that is equal to . \nAs there are sphere in FCC unit cell \nThe volume of four spheres is given by
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In FCC, the corner spheres are in touch with the face centred sphere, so the relation between the edge length and radius of the sphere is given by
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Substituting the above values in the below equation and solving:
The packing fraction for a FCC crystal is the maximum in all crystals.
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Embibe Experts Chemistry Solutions for Exercise - Embibe Experts Solutions for Chapter: Solid State, Exercise 1: Assam CEE 2016
Attempt the free practice questions on Chapter 7: Solid State, Exercise 1: Assam CEE 2016 with hints and solutions to strengthen your understanding. EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR CHEMISTRY solutions are prepared by Experienced Embibe Experts.
Questions from Embibe Experts Solutions for Chapter: Solid State, Exercise 1: Assam CEE 2016 with Hints & Solutions
atoms occupy the corners of an f.c.c. unit cell and atoms occupy the face-centered positions, and atoms are not present in two corners of each unit cell. The formula of the compound is