Answer to Question #246359 in Physical Chemistry for Eksdi

Question

 Strontium forms a face centered cubic unit cell and has a density of 2.64 g/cm³. What is the radius of a strontium atom?

Answer 1

D = [ZM/A]/a³

2.64 grams /cm³ = [(4 atoms)(87.62 grams/mol) / (6.023 x 10²³ atoms/mole)] / a³

a³ = 2.205 x 10⁻²²

a = 6.041 x 10⁻⁸ cm

The relationship between the side of the cube and the radius of the cell is a/r = 2√2 where a is the side of the cube and r is the radius of the atom.

a/r = 2√2

6.041 x 10⁻⁸ cm/r = 2√2

r = 2.136 x 10⁻⁸ cm