Question

Q-3. If silver atoms follow a face-centered cubic unit cell pattern, what is the length of this unit cell if the atomic radius is 144.4 pm? a. 144 pm b. 179 pm c. 408 pm d. 635 pm Q-4. If iridium has a density of 23.3 g/cm radius of the iridium atom? and forms a face-centered cubic lattice, what is the atomic a. 135.7 pm b. 203.7 pm c. 271.4 pm d. 648.0 pm Q-5. The ability to bend a metallic solid is described by the metal's: a. mobility b. ductility c. malleability d. polymeric breakpoint

Answer 1

3)

for FCC:

length of one face diagonal = 4*r

a*sqrt(2) = 4*r

a * 1.4142 = 4*144.4 pm

a = 408 pm

Answer: c

4)

since the cubic cell is Face Centred Cubic, the value of Z=4

Molar mass = 192.2 g/mol

d = (Z*M)/(a^3*NA)

23.3 = (4*192.2)/(a^3*(6.022*10^23))

a^3 = 5.479*10^-23 cm^3

a = 3.798*10^-8 cm

a = 379.8 pm

Now use:

length of one face diagonal = 4*r

a*sqrt(2) = 4*r

379.8 * 1.4142 = 4*r

r = 134.3 pm

Answer: a