How many atoms1 cm3 for silicon?

Answer 1

• Number of atoms in a unit cell:
• • 4 atomscompletely inside cell
  • Each of the 8 atoms on corners are shared among cells

 count as 1 atom inside cell

• Each of the 6 atoms on the faces are shared among 2

cells  count as 3 atomsinside cell

• • Total number inside the cell = 4 + 1 + 3 = 8
• Cell volume:

(.543 nm)3 = 1.6 x 10-22 cm3

• Density of silicon atoms

= (8 atoms) / (cell volume) = 5 x 1022 atoms/cm3