MaterialsContributions by:

John L. Falconer & Will MedlinDepartment of Chemical and Biological Engineering

University of ColoradoBoulder, CO 80309-0424

Sample A is an equimolar physical mixture of Si and Ge. Sample B is a Si0.5Ge0.5 solid solution. Which measurements will be different for the two samples?

A. Elemental analysis and x-ray diffraction

B. X-ray diffraction

C. Absorption spectrum

D. Absorption spectrum and x-ray diffraction

E. Elemental analysis

Below is a 2-dimensional representation of a crystal structure where each circle represents a single atom. Each lattice/unit cell contains ________ atoms.

A. 1

B. 2

C. 3

D. 4

A unit cell of a simple cubic crystal is represented below. If each corner contains an atom, how many atoms are there per unit cell?

A. 1

B. 2

C. 3

D. 4

E. 8

A unit cell of a simple cubic crystal structure is represented below. If each corner contains an atom, what is the coordination number of each atom?

A. 4

B. 6

C. 8

D. 10

E. 12

In a space-filling representation, the unit cell size is limited by the close-packing of spherical atoms, where the surfaces of the atoms are in contact. For a simple cubic unit cell of this type, how are atom center distance, d, and atom radius, r, related?

A. d = r

B. d = 2r

C. d = 3r

D. d = 4r

d

A corner atom is part of how many unit cells in this simple cubic structure?

A. 1

B. 2

C. 4

D. 8

In the face-centered cubic (FCC) crystal structure, an atom is on each corner and each side of the unit cell. How many atoms are in the unit cell?

A. 1

B. 2

C. 4

D. 14

E. None of the above

In a face-center cubic structure, the atoms are close-packed along the face diagonal. What is the coordination number of a metal atom in this structure?

A. 2

B. 4

C. 6

D. 8

E. 12

In the body-centered cubic (BCC) crystal structure, an atom is on each corner and one atom (blue atom) is in the center of the unit cell. How many atoms are in the unit cell?

A. 1

B. 2

C. 4

D. 8

E. 9

In the body-centered cubic (BCC) crystal structure, an atom is on each corner and one atom (blue atom) is in the center of the unit cell. What is the coordination number for each atom?

A. 4

B. 6

C. 8

D. 12

Which crystal structure is body center cubic?

A. C.

B. D.

A zinc sulfide crystal structure is shown. What type of unit cell is defined by just the green sulfide ions?

A. Simple cubic

B. Body-centered cubic

C. Face-centered cubic

D. None of the above

A layer sequence for an FCC metal is shown. A close-packed plane is comprised of six atoms. If atoms 2, 4, 5 are three of the six atoms, which other three atoms are need to define the plane?

A. 11, 13, 14

B. 6, 9, 12

C. 7, 8, 14

D. 6, 9, 10

1 2

4 3

5

6

79

8

Z = 0

Z = 1/2 Z = 110 11

13 12

14

Which structure is the FCC (110) plane?

A CB

FCC unit cell

Which structure is the FCC (001) plane?

A CB

FCC unit cell

Which structure is the FCC (111) plane?

A CB

FCC unit cell

In a zinc sulfide (ZnS) crystal structure, each zinc ion (blue) sits between four sulfide ions (white). Given a ZnS layer sequence, which sulfide ions surround the indicated zinc ion?

A. 1, 4, 7, 8

B. 1, 3, 4, 7

C. 1, 3, 6, 7

D. 1, 4, 7, 9

1 2

4 53

6

87

9

Z = 0 Z = 1/4

Z = 1/2 Z = 3/4

How many sulfide ions (green) are in a zinc sulfide unit cell?

A. 1

B. 2

C. 3

D. 4

Vanadium, molybdenum, and sodium all have a body-centered cubic structure. Given the following atomic radii, which two metals are most likely to form a sold solution?

A. Vanadium, molybdenum

B. Vanadium, sodium

C. Molybdenum, sodium

Metal Atomic radii

V 0.131Mo 0.136Na 0.186

For a two-plane, octahedron arrangement of identical spheres, there will be two differently-sized gaps. One gap will be within the plane, the other gap will be between planes. Which gap will be smaller?

A. Within the plane

B. Between the planes

C. The gaps are the same size

Between planes

Within plane

When a copper wire is heated, it becomes more malleable because ___________________________.

A. the bonds have been weakened

B. the wire has fewer atomic level defects

C. the wire has more atomic level defects

D. the density is lower

E. there is more space inside the crystal lattice

Atoms in a solid _____________________________.

A. cannot move, only electrons move

B. may move through vacancies in a crystal lattice

C. may move in the spaces between atoms in a crystal lattice

D. can move through both vacancies and in the spaces between atoms in a crystal lattice

E. none of the above

Gallium(Ga) can be mixed with two other elements to form a solution. Possible elements include aluminum(Al), arsenic(As), and phosphate(P). If 0 < x < 1, which gallium alloys could be solid solutions?

A. GaxAl1-xAs ; GaAlxAs1-x

B. GaxAl1-xAs ; GaPxAs1-x

C. GaPxAs1-x ; GaAlxAs1-x

D. GaPxAs1-x ; GaxP1-xAs

5 B

6 C

7 N

8 O

13 Al

14 Si

15 P

16 S

31 Ga

32 Ge

33 As

34 Se

49 In

50 Sn

51 Sb

52 Te

Buckminsterfullerene, C60, is face-centered cubic in crystalline form. If a fullerene was saturated with potassium, by placing a potassum atom in every tetrahedral hole and every octahedral hole, the chemical formula would be ____.

A. KC60

B. K2C60

C. K3C60

D. K4C60

E. K6C60

How many zinc ions (green) are in a zinc sulfide unit cell?

A. 1

B. 2

C. 3

D. 4

How many atoms are in the following layer sequence of a diamond structure?

A. 4

B. 6

C. 8

D. 13

Z = 0 Z = 1/4

Z = 1/2 Z = 3/4

What is the coordination number for a diamond structure?

A. 4

B. 6

C. 8

D. 10

What is the coordination geometry of a diamond structure?

A. Tetrahedral

B. Square

C. Octahedral

D. Cubic

In the two-dimensional square packing shown below, what is the coordination number of the central atom?

A. 2

B. 4

C. 6

D. 8

Which part of a face-centered cubic crystal surface is likely to chemically etch faster?

A. 111 plane

B. 100 plane

C. Grain boundary

D. Vacancy

A system contains an equimolar vapor/liquid mixture of components A and B. The saturated pressure of A is greater than that of B. If the system is an ideal gas, which plot represents the effect of raising the system pressure on the vapor/liquid fractions of component A?

yA

xAxAyA

yA xAyA xA Pa

sat > PBsat

A. B.

D. E.

P P P

P P

1.0

0

1.0

0yA

xA

C.

1.0

0

1.0

0

1.0

0

For this Cu/Ni phase diagram, which cooling curve results for a 50/50 mixture?

Tem

p.

Time

A

Tem

pera

ture Liquid

Solid

100% Cu

100% Ni

50/50

Time

BTe

mp.

Time

C

Tem

p.Time

D

Tem

p.

Time

E

Tem

p.

Magnesium and silicon form Mg2Si under certain conditions. What phases and how much of each will be present for a 60 mol% Si mixture at 1000 K?

A. 1 phase that is 57% Si

B. 2 phases; 57% is Mg2Si

C. 2 phases; 40% is Mg2Si

D. 2 phases; 57% is pure Mg

E. 2 phases; 57% is pure Si xSi

Tem

pera

ture

(K)

0 1

Liquid

800

1700

Mg Si

A Pt/Ag alloy containing 62% Ag is initially at 1600°C . As it cools, what phases are observed?L represents liquid and α and β are solids.

A. L+α, L+α+β, L+β, β, α+β

B. L+α, L+β, α, α+β

C. L+α, L+α+β, L+β, α+β

D. L+α, L+β, α+β

E. L+α, L+β, β , α+βWt % Ag0 100

1800

Tem

p. (°

C)

LL+α

L+β

β

α

α+β

Cu/Pb alloys can form several combinations of phases between two liquids (L1 and L2) and alpha (α) and beta(β) solid. Given some of thephases, what phase(s) is/are present at the pointindicated?

A. L2+α

B. L1+β

C. L1+L2

D. α+β Wt % Pb0 100

Tem

pera

ture

L+ αL

α + β

A Si-Mg mixture containing 40 mol% Si at 1000 K (the blue dot in the figure) contains ____________.

A. a single solid phase

B. a mixture of pure Si and pure Mg

C. a mixture of Si and Mg2Si

D. none of the above

xSi

Tem

pera

ture

(K)

0 1

Liquid

800

1700

Mg2Si

For the binary phase diagram for components A and B, what fraction of the mixture is liquid at point indicated by the black dot?

A. 30%

B. 45%

C. 50%

D. 55%

E. 70% 0 1Weight frac B

Tem

pera

ture

Liquid

Solid