An element in its solid phase forms a cubic crystal lattice (see Problem 33) with mass density 7950 kg/m3. The smallest spacing between two adjacent atoms is 0.227 nm. What is the element’s atomic mass number?

Data From Problem# 33:

The atomic mass number of copper is A = 64. Assume that  atoms in solid copper form a cubic crystal lattice. To envision  this, imagine that you place atoms at the centers of tiny sugar cubes, then stack the little sugar cubes to form a big cube. If  you dissolve the sugar, the atoms left behind are in a cubic crystal lattice. What is the smallest distance between two copper atoms?