# chemistry

Platinum has a face-centered cubic crystal structure and a density of 21.5 g/cm3. What is the radius of the platinum atom?

1. The fcc has 4 atoms/unit cell.
Mass of 1 atom Pt = 195.08/6.02 x 10^23.
Mass of unit cell is 4 times that.
Then m = volume x density. You know density and mass, calculate volume of unit cell. From volume = a3 you can calculate a (the length of the side).
For a fcc unit cell, 4*radius = a*21/2. You know a and that allows you to calculate radius.
Post your work if you get stuck.
You know

posted by DrBob222
2. 98

posted by Anonymous
3. is not 98. try 139

posted by Anonymous,

First Name

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