CHEM102 Lecture Notes - Ion, Zinc Sulfide, Illinois Route 1
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CHEM102 Full Course Notes
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The structure gives the cubic-closest packed (faced-centred cubic) unit cell. Abc closest packed structure gives rise to face-centred cubic unit cell. To determine crystal structures, light of short wavelength must be used. Path difference for the two x-ray beam = 2dsin . For in phase waves, path difference = n and a spot is seen. Knowing the angle and the wavelength , the distance between the particles can be determined. X-ray if wavelength 1. 54 were used to analyze an aluminium crystal. A reflection was produced at = 19. 3o. Assuming n = 1, calculate the distance d between the planes of atoms producing this reflection. n . = 2. 33 (1) (1. 54 ) (2) (sin 19. 3o) Strategy: it is important for you to find the straight line which joins the centres of all spheres that touch each other. By x-ray diffraction, the edge of the cubic cell is found to be 287 pm.
