In: Physics
The atomic mass number of copper is 64. Assume that atoms in solid copper form a cubic crystal lattice. To visualize this, imagine stacking tiny sugar cubes into a big cube. If you pretend there is a copper atom in the middle of each sugar cube, then dissolve the sugar away, the copper forms a cubic lattice. What is the smallest distance between copper atoms?
Hint: The answer is 0.228nm, but you must still show all your work with clear understanding!
Density of copper
Atomic mass number of copper is . That is mass of one mole of copper atoms is .
One mole of copper atoms means one Avogadro number of copper atoms.
Hence atoms weigh .
Volume of one mole of copper atoms is
Smallest distance between copper atoms is equal to size of one unit cell (tiny sugar cube)
Let this size be . Hence each atom occupies a volume .
Volume occupied by one mole of copper atoms is
Hence
Hence smallest distance between copper atoms is