question_answer 48)

Aluminium crystallises in a cubic close-packed structure. Its metallic radius is 125 pm. (a) What is the length of the side of the unit cell? (b) How many unit cells are there in 1.00 cm3 of aluminium?  

Answer:

(a) r = 125 pm For cubic close packed structure,   (b) Volume of unit cell, a3 = (354 x 10?12 cm)3 = 44 361 x 10?30 cm3 Now, 44361 x 10?30 cm3 contains = 1 unit cell = 226 x 1022 unit cells