Question

Iridium has a cubic unit celll - body centre cube

How many iridium atoms occur in each unit cell? and Given the unit cell has a density of 22.56g cm^-3 calculate the atomic radius of the element? Please show all workings thank you.

Answer 1

body centre unit cell cornor atom one and body centre atom one
total atoms in body cetre unit cell is 1+1 =2
density = mass/volume
        = 2* atomic mass/6.023*10^23 *(edge lengh)^3
22.56   =2*192.22/6.023*10^23*a^3
a^3     = 384.44/135.8788*10^23
        = 2.829*10^-23
        =28.29*10^-24
a      = 3.047*106-8
   r     = root of 3*a/4
          = 1.73*3.047*10^-8/4
    r     = 1.3178*10^-8
          = 1.3178A⁰