Question: how many silicon atoms are there in each unit cell?
Answer: Unit cell: 8 atoms at corners at 1/8 each in cell 6 atoms in faces at ½ each in cell 4 atoms within cell. Thus total of 8 Si atoms per unit cell. Each Si atom weighs 28 atomic mass units (1.66 E-24 grams). Dimension of unit cell is 5.43 angstroms or 5.43 E-08 cm.