A cubic unit cell is made up of X and Y elements. If X are present on the corners of the cube and Y are present on centres of faces of cube, then find the formula of the compound. (Hr. S.B. 2018)
Solution: In a cube, X atoms are at the 8 corners, each shared by 8 cubes. Therefore,
The number of X atoms in the unit cell is 8/8 = 1
Y atoms are at the centres of 6 faces and each face is shared by two cubes. Therefore,
The number of Y atoms = 6/2 = 3
The formula of the compound = XY3
