3 55 points previous answers ncsugenchem102labv1

3. 5/5 points | Previous Answers NCSUGenChem102LabV1 6.POST.03.
Many metals pack in cubic unit cells. The density of a metal and length of the unit cell can be used to determine the
type for packing. For example, iron has a density of 7.87 g/cm
3
and a unit cell side length a of 2.87
Å
. (1
1. 10
-8
cm.)
(a) How many iron atoms are in exactly 1 cm
3
Å
=
?
(b) How many unit cells are in exactly 1 cm
3
?
(c) How many iron atoms are there per unit cell?

(d) The atoms/unit cell suggests that iron packs as a body-centered body-centered unit cell.
Knowledge of the type of packing and side length a of the unit cell will allow calculation of the atomic radius, using
one of the equations below. You may need to draw the unit cell to determine which formula to use to calculate the
atomic radius.
(e) What is the atomic radius of iron ?
1.24 1.24
Å
Additional Materials

Solid State Modeling
4. 5/5 points | Previous Answers NCSUGenChem102LabV1 6.POST.04.
Green checks and red X's are not displayed for this question.
Use what you learned in lab about atoms in cubic structures to answer the following questions about a solid whose
crystal structure was found to have atoms "A" in corner and center sites and "B" in the face sites of a cubic unit cell.
How many "A"s are there in a unit cell?
2 2 "A"(s)
How many "B"s are there in a unit cell?
3 3 "B"(s)