Question

5. Aluminium crystallizes in cubic close
packed structure with unit cell edge
length of 353.6 pm. What is the radius of
Al atom? How many unit cells are there
in 1.00 em' of AI? (125 pm, 2.26x102)​

Answer 1

Answer:

Explanation:

It is given that aluminum crystallises in a cubic closed packed structure.

Its metallic radius is 125 pm.

(i) For cubic close-packed structure

a=2  

2

​  

r=2  

2

​  

×125=354 pm

Here, a is the edge length of the unit cell and r is the atomic radius.

(ii) Volume of one unit cell

=a  

3

=(354 pm)  

3

=4.4×10  

−23

 cm  

3

 

(1 pm=10  

−10

 cm)

Number of unit cells in 1.00cm  

3

=  

4.4×10  

−23

cm  

3

 

1.00cm  

3

 

​  

=2.27×10  

22