BME 350 Exam 2 questions and Answers Reviewed
Crystal systems and crystal lattices serve all purposes listed as follows except: **
Answ** specifying bond types, specifying important engineering properties
Crystal systems and Bravais lattices are used by materials scientists to do which of the
following? ** Answ** describe direction, position, and planes of atoms in crystals
A crystal lattice is made of ** Answ** points
A crystal structure is composed of ** Answ** atoms
Which of the following are not among the Hume Rothery rules that specify the relative
degree of solubility of a solute atom in a solid solvent ** Answ** similar stacking
layers, same number of protons, same row on the periodic table, same unit cell???
How many parameters are available to crystallographers to quantify the general 3D unit
cell of a crystal ** Answ** 6
What is the major difference between FCC and HCP unit cells ** Answ** Significant
differences is material properties
true or false: lattice points do not refer to specific atoms in the crystal ** Answ** True
why are x-rays useful for studying materials? ** Answ** x-rays can reveal
quantitative material structure information, wavelength of x-rays is comparable to the
distance between atoms
Assuming no variation in atomic dimensions among the considered structures, which of
the following crystal structures have the most empty space in a unit cell? ** Answ**
body centered cubic structures??
Which of the following is not one of the types of bravais lattices noted in your text book?
** Answ** self-centered
What are the 14 crystal lattices? ** Answ** simple cubic, body centered cubic, face
centered cubic, simple tetragonal, simple orthorhombic, body centered orthorhombic,
base centered orthorhombic, face-centered orthorhombic, rhombohedral, hexagonal,
simple monoclinic, base centered monoclinic, triclinic
True or false: more than one atom can be associated with a lattice point ** Answ**
true
true or false: while most metals are 99% crystalline, they are generally not composed of
a perfect single crystal ** Answ** true
For assistance with assignments contact
, at 573 deg C, silica (SiO2) did not alter its fundamental HCP crystal structure, but the
________ of the crystal tetrahedra composing this structure did change ** Answ**
orientations
The phase change of silica at 573 deg c is important because the crystal structure at
this temp becomes _______ when it assumes the beta-quartz structure ** Answ**
less dense
for metals in general, as grain size increases.... ** Answ** strength decreases
What expression is most relevant to materials engineers who study atomic order in
atoms ** Answ** dS>0 (second law of thermodynamics)
Miller bravais index (h k i l) is used in HCP systems. This differs from Miller indices (h k
i) used in BCC and FCC systems. The relationship h+k=-i relates the two. What is the
fundamental basis for this? ** Answ** 3 points define a plane, the 4th index of miller-
bravais system is redundant in 3D and crystallographers prefer simplicity
X-ray diffraction involves ______ btw the x-ray photons and the _______ of the target
atoms ** Answ** Elastic collisions, valence electrons
True or false: Braggs law of diffraction, while useful for determining crystal dimensions,
applies only for primitive unit cells like simple cubic and tetragonal systems having
lattice points at corners only ** Answ** true
How to define a plane with miller indices ** Answ** take inverse of axial intercepts.
ex intercepts at 1 -> 1/1. intercepts at 1/2 reciprocal is 2. never intercepts 1/inf = 0.
regarding crystal structures, a dislocation can be described as a ** Answ** line or
plane of atoms added to a crystal structure
edge dislocation ** Answ** -extra half plane of atoms inserted in a crystal structure
-b perpendicular to dislocation line
screw dislocation ** Answ** spiral planar ramp resulting from shear deformation
b parallel to dislocation line
What is the key material property difference between two crystals with point defects.
One with schotky and one with frenkel ** Answ** difference in density
which of the following is a type of "line" defect in a crystal ** Answ** edge, screw
true or false: the burger's vector b is useful for describing the magnitude and type of
crystal dislocation ** Answ** true
For assistance with assignments contact
Crystal systems and crystal lattices serve all purposes listed as follows except: **
Answ** specifying bond types, specifying important engineering properties
Crystal systems and Bravais lattices are used by materials scientists to do which of the
following? ** Answ** describe direction, position, and planes of atoms in crystals
A crystal lattice is made of ** Answ** points
A crystal structure is composed of ** Answ** atoms
Which of the following are not among the Hume Rothery rules that specify the relative
degree of solubility of a solute atom in a solid solvent ** Answ** similar stacking
layers, same number of protons, same row on the periodic table, same unit cell???
How many parameters are available to crystallographers to quantify the general 3D unit
cell of a crystal ** Answ** 6
What is the major difference between FCC and HCP unit cells ** Answ** Significant
differences is material properties
true or false: lattice points do not refer to specific atoms in the crystal ** Answ** True
why are x-rays useful for studying materials? ** Answ** x-rays can reveal
quantitative material structure information, wavelength of x-rays is comparable to the
distance between atoms
Assuming no variation in atomic dimensions among the considered structures, which of
the following crystal structures have the most empty space in a unit cell? ** Answ**
body centered cubic structures??
Which of the following is not one of the types of bravais lattices noted in your text book?
** Answ** self-centered
What are the 14 crystal lattices? ** Answ** simple cubic, body centered cubic, face
centered cubic, simple tetragonal, simple orthorhombic, body centered orthorhombic,
base centered orthorhombic, face-centered orthorhombic, rhombohedral, hexagonal,
simple monoclinic, base centered monoclinic, triclinic
True or false: more than one atom can be associated with a lattice point ** Answ**
true
true or false: while most metals are 99% crystalline, they are generally not composed of
a perfect single crystal ** Answ** true
For assistance with assignments contact
, at 573 deg C, silica (SiO2) did not alter its fundamental HCP crystal structure, but the
________ of the crystal tetrahedra composing this structure did change ** Answ**
orientations
The phase change of silica at 573 deg c is important because the crystal structure at
this temp becomes _______ when it assumes the beta-quartz structure ** Answ**
less dense
for metals in general, as grain size increases.... ** Answ** strength decreases
What expression is most relevant to materials engineers who study atomic order in
atoms ** Answ** dS>0 (second law of thermodynamics)
Miller bravais index (h k i l) is used in HCP systems. This differs from Miller indices (h k
i) used in BCC and FCC systems. The relationship h+k=-i relates the two. What is the
fundamental basis for this? ** Answ** 3 points define a plane, the 4th index of miller-
bravais system is redundant in 3D and crystallographers prefer simplicity
X-ray diffraction involves ______ btw the x-ray photons and the _______ of the target
atoms ** Answ** Elastic collisions, valence electrons
True or false: Braggs law of diffraction, while useful for determining crystal dimensions,
applies only for primitive unit cells like simple cubic and tetragonal systems having
lattice points at corners only ** Answ** true
How to define a plane with miller indices ** Answ** take inverse of axial intercepts.
ex intercepts at 1 -> 1/1. intercepts at 1/2 reciprocal is 2. never intercepts 1/inf = 0.
regarding crystal structures, a dislocation can be described as a ** Answ** line or
plane of atoms added to a crystal structure
edge dislocation ** Answ** -extra half plane of atoms inserted in a crystal structure
-b perpendicular to dislocation line
screw dislocation ** Answ** spiral planar ramp resulting from shear deformation
b parallel to dislocation line
What is the key material property difference between two crystals with point defects.
One with schotky and one with frenkel ** Answ** difference in density
which of the following is a type of "line" defect in a crystal ** Answ** edge, screw
true or false: the burger's vector b is useful for describing the magnitude and type of
crystal dislocation ** Answ** true
For assistance with assignments contact
