Question

An element crystallizes in a body-centered cubic lattice. The edge of the unit cell is 0.286 nm, and the density of the crystal is 7.92 g/cm3 . Calculate the atomic weight of the element

Answer 1

Answer: 6.94

Explanation: Density d=  

a  

3

×N  

A

​  

 

Z×M

​  

 

a=0.351 nm=3.51×10  

−8

 cm

d=0.533 g/cm  

3

 

Z=2

d=  

a  

3

×N  

A

​  

 

Z×M

​  

 

M=  

Z

d×a  

3

×N  

A

​  

 

​  

 

M=  

2

0.533×(3.51×10  

−8

)  

3

×6.023×10  

23

 

​  

 

M=6.94