The radius of an atom of aluminum is 143pm and there are 10^12 in a meter. The aluminum is a 3x3cm square. The density is 2.70 g/cm^3. I found the mass to be 0.03g. I found the volume to be 0.09cm^3Good quality standard
aluminum foil such as Reynolds brand is 0.007 inches thick. If aluminum atoms are indeed 143 picometers in radius then the foil would be 2,486,713 atoms thick. Of course, the thickness is not controlled to a tolerance of one atom. (Cheaper brands are about 0.0060 to 0.0065 inches thick.) The ionic radius of aluminum is commonly accepted to be 72 pm, and as of 2008 a covalent radius of 121 pm. . .Other related question