Help me with atomic physics or chemistry?

I am not certain about these, but here is my approach. I hope it helps.

The mass of the gold is 2.2 g; the atomic mass of gold is 170 g/mol so the foil contains 0.0129 moles; each mole contains 6.02*10^23 atoms, so the foil has a total of 7.77*10^21 atoms. Each FCC unit cell has the equivalent of 4 atoms, so the volume of the foil contains 1.94*10^21 unit cells. The volume of the foil is 9*(5*10^-3]*2.54 = 0.114 cm³. The volume of a single unit cell is then 0.114/1.94*10^21 = 5.88*10^-23 cm³. The cell is then a cube with edges 3.89*10^-8 cm. The nearest neighbor atoms are the corner-to-centerface. The distance is half the diagonal of the cubic face = ½*√[2]*2.45*10^-8 = 2.75*10^-8 cm = 2.75 Å

Silicon has a diamond cubic unit cell which is FCC plus two additional atoms inside each cell giving the equivalent of 6 atoms per cell. The nearest neighbor distance is ¼ the cell width. If this remains the same, then the cell width is 4*2.75 = 11.0 Å; The cell volume is now 1.33*10^-21 cm³. There are now 7.77*10^21/6 = 1.295*10^21 cells. The total volume is then 1.295*10^21*1.33*10^-21 = 1.72 cm³; the thickness is then 0.191 cm.

If the lattice constant is unchanged, then the size of the unit cube is unchanged at 5.88*10^-23 cm³; however, there are now 1.295*10^21 cells for a total volume of 0.0761 cm³ and a thickness of 0.846 cm

Source(s): http://en.wikipedia.org/wiki/Face-centered_cubic
http://www.uncp.edu/home/mcclurem/courses/chm226/i…
http://en.wikipedia.org/wiki/Diamond_cubic