# Calculating atomic radius from weight + density

by physicsnnewbie
 P: 49 1. The problem statement, all variables and given/known data Calculate the radius of a palladium atom, given that Pd has an FCC crystal structure, a density of 12.0g/cm3, and an atomic weight of 106.4g/mol 2. Relevant equations Pd contains 4 atoms per unit cell. unit cell edge lengh = 2*Radius*sqrt(2) 3. The attempt at a solution calculate atom weight: 106.4/6.0221418e23 = 1.7668133e-22 calculate unit cell weight: 1.7668133e-22*4 = 7.0672532e-22 calculate unit cell volume in cm3: 7.0672532e-22/12 = 5.8893777e-23 convert to nm3: 5.8893777e-23*(10^7)^3 = 0.0588938 calculate edge length: 0.0588938^(1/3) = 0.3890659 calculate radius: 0.3890659/2 = 0.194533 my answer: 0.194533nm correct answer: 0.138nm I cant figure out what i've done wrong here.
 P: 49 I figured it out. I got confused and thought 2*sqrt(2) was equal to 2. So silly!

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