Calculating the Mass of an Aluminum Unit Cell

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Aluminum's density is 2.699 g/cm3, and it has a face-centered cubic (fcc) crystal structure. The mass of a unit cell is calculated by considering that there are 4 atoms per unit cell due to the geometry of the fcc arrangement. Each atom contributes partially to the unit cell, leading to the total mass calculation. The final mass of the aluminum unit cell is determined to be 1.792 x 10^-22 g. Understanding the geometry of the fcc lattice is essential for accurate calculations.
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Aluminum has a density of 2.699 g/cm3 , and the atoms are packed in a face-centered cubic crystal lattice. Find the mass of a unit cell.

-----I already know the answer is 1.792*10^-22g/unit cell

I have a question about how you get the answer:
I know you multiply 4.480*10^-23g * 4 atoms/1 unit cell= the answer

where does the 4 atoms come from?
 
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Geometry of the cell. In fcc all atoms lie on the cell walls, so they are only partially belong to the cell. Sum these fractions.
 
Borek said:
Geometry of the cell. In fcc all atoms lie on the cell walls, so they are only partially belong to the cell. Sum these fractions.

got it, thanks!
 
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