JEE MainChemistrySolid State
In a crystalline solid, atoms of element X form a cubic close-packed (ccp) lattice. Atoms of element Y occupy all the octahedral voids and 25 % of the tetrahedral voids. The total number of atoms (of X and Y together) present in one unit cell of the solid is ________.
Correct answer
10
Step-by-step solution
In a cubic close-packed (ccp) lattice, the effective number of atoms of X per unit cell is 4 . For a ccp lattice with Z = 4 , the number of octahedral voids is equal to Z = 4 , and the number of tetrahedral voids is equal to 2Z = 8 . Atoms of element Y occupy all the octahedral voids and 25 % of the tetrahedral voids. Number of Y atoms from octahedral voids = 4 Number of Y atoms from tetrahedral voids = 25 100 8 = 2 Total number of Y atoms per unit cell = 4 + 2 = 6 Total number of atoms per unit cell = Atoms of X +