Baykko

The covalent radius of an aluminum atom is 1.18 x 10^-8 cm. Assuming that in aluminum foil,the atoms are packed one on top of each other, how many atoms thick is a sheet of aluminum foil? (if aluminum thickness= 0.0017) for this.. ive tried dividing the thickness with the radius/diameter, giving me answer of around 14k and 7k but not sure if that is correct or what is the right way to solve it. then i have no idea what to do for this problem, A cube of aluminum of side 2.00cm has a mass of 21.60g. Using the covalent radius of an aluminum atom, calculate the volume of the "empty space" inside the cube.