MSE Midterm Questions with Verified
Answers
A deeper curve for a bonding potential energy curve means - ANSWER-larger melting
temperature/bond energy
a shallower curve for a bonding potential energy curve means - ANSWER-smaller
melting temp/bond energy
a skinnier curve for a bonding potential energy curve means - ANSWER-larger elastic
modulus, E
A wider curve with more curvature for a bonding potential energy curve means -
ANSWER-smaller elastic modulus, E
A less symmetric curve for a bonding potential energy curve means - ANSWER-larger
coefficient of linear expansion
a more symmetric curve for a bonding potential energy curve means - ANSWER-
smaller coefficient of linear expansion
Which types of bonding are found in polymers - ANSWER-covalent and secondary
FCC crystal structure has ___ atoms, a coordination number of ___, an atomic packing
factor of ___, and a side length (a) of ___ - ANSWER-4, 12, 0.74, 4r/sqrt(2)
BCC crystal structure has ___ atoms, a coordination number of ___, an atomic packing
factor of ___, and a side length (a) of ___ - ANSWER-2, 8, 0.68, 4r/sqrt(3)
Simple cubic crystal structure has ___ atoms, a coordination number of ___, an atomic
packing factor of ___, and a side length (a) of ___ - ANSWER-1, 6, 0.52, 2r
HCP crystal structure has ___ atoms, a coordination number of ___, and an atomic
packing factor of ___ - ANSWER-2, 12, 0.74
Materials that have the most ionic bonding (%ionic character) - ANSWER-Bonds
between a metal and nonmetal with greatest difference in electronegativity
what kind of defect takes place when a different atom of nearly the SAME size is added
into a pure lattice of another element - ANSWER-substitutional impurity
What does isotropic mean? Materials that have isotropic mechanical properties? -
ANSWER-Isotropic means the materials properties are the same in all directions.
Polycrystalline materials with randomness of grains or equiaxed grains.
, What does anisotropic mean? Materials that have anisotropic mechanical properties? -
ANSWER-Anisotropic means the materials properties vary with direction. Single crystal
material, Polycrystalline with elongated, high texture, aligned grains will be anisotropic.
What is a materials property? Examples? - ANSWER-A materials property is intrinsic,
does not change with amount or shape. Density, Tm, yield strength, coeff of linear
expansion, young's modulus, fracture toughness (Kic), resistivity, and conductivity are
all materials properties.
How do the values of Youngs modulus, coeff of linear expansion, and melting
temperature rank for ceramics? - ANSWER-High E, Low a, High Tm
How do the values of Youngs modulus, coeff of linear expansion, and melting
temperature rank for metals? - ANSWER-Moderate E, Moderate a, Moderate Tm
How do the values of Youngs modulus, coeff of linear expansion, and melting
temperature rank for polymers? - ANSWER-Low E, High a, Low Tm
The number of vacancies in a crystal ____ as temperature increases - ANSWER-
increases
T/F: some materials will experience a transition from ductile to brittle fracture with a
decrease in temperature? - ANSWER-True
Why do ceramics generally have a higher melting temperature than metals? -
ANSWER-Ceramics generally have stronger bongs than metals
A line of distorted or incomplete bonds in a crystal describes a ____________ -
ANSWER-dislocation
Why does a metal expand when heated? - ANSWER-The asymmetry in the atomic
bonding potential curve causes the atoms to move farther apart on average when their
energy increases.
Rank density of classes of materials from lowest to highest - ANSWER-
polymers<ceramics<metals
(C2F4)n has which types of bonding? - ANSWER-Covalent and secondary
Amorphous glasses tend to be more or less dense than their crystalline counterparts? -
ANSWER-less
Why is dislocation slip difficult in ceramic materials? - ANSWER-Because bonding in
ceramics can be directional and for dislocations to move in ceramics ions with like
charges could be required to move closer to each other
Answers
A deeper curve for a bonding potential energy curve means - ANSWER-larger melting
temperature/bond energy
a shallower curve for a bonding potential energy curve means - ANSWER-smaller
melting temp/bond energy
a skinnier curve for a bonding potential energy curve means - ANSWER-larger elastic
modulus, E
A wider curve with more curvature for a bonding potential energy curve means -
ANSWER-smaller elastic modulus, E
A less symmetric curve for a bonding potential energy curve means - ANSWER-larger
coefficient of linear expansion
a more symmetric curve for a bonding potential energy curve means - ANSWER-
smaller coefficient of linear expansion
Which types of bonding are found in polymers - ANSWER-covalent and secondary
FCC crystal structure has ___ atoms, a coordination number of ___, an atomic packing
factor of ___, and a side length (a) of ___ - ANSWER-4, 12, 0.74, 4r/sqrt(2)
BCC crystal structure has ___ atoms, a coordination number of ___, an atomic packing
factor of ___, and a side length (a) of ___ - ANSWER-2, 8, 0.68, 4r/sqrt(3)
Simple cubic crystal structure has ___ atoms, a coordination number of ___, an atomic
packing factor of ___, and a side length (a) of ___ - ANSWER-1, 6, 0.52, 2r
HCP crystal structure has ___ atoms, a coordination number of ___, and an atomic
packing factor of ___ - ANSWER-2, 12, 0.74
Materials that have the most ionic bonding (%ionic character) - ANSWER-Bonds
between a metal and nonmetal with greatest difference in electronegativity
what kind of defect takes place when a different atom of nearly the SAME size is added
into a pure lattice of another element - ANSWER-substitutional impurity
What does isotropic mean? Materials that have isotropic mechanical properties? -
ANSWER-Isotropic means the materials properties are the same in all directions.
Polycrystalline materials with randomness of grains or equiaxed grains.
, What does anisotropic mean? Materials that have anisotropic mechanical properties? -
ANSWER-Anisotropic means the materials properties vary with direction. Single crystal
material, Polycrystalline with elongated, high texture, aligned grains will be anisotropic.
What is a materials property? Examples? - ANSWER-A materials property is intrinsic,
does not change with amount or shape. Density, Tm, yield strength, coeff of linear
expansion, young's modulus, fracture toughness (Kic), resistivity, and conductivity are
all materials properties.
How do the values of Youngs modulus, coeff of linear expansion, and melting
temperature rank for ceramics? - ANSWER-High E, Low a, High Tm
How do the values of Youngs modulus, coeff of linear expansion, and melting
temperature rank for metals? - ANSWER-Moderate E, Moderate a, Moderate Tm
How do the values of Youngs modulus, coeff of linear expansion, and melting
temperature rank for polymers? - ANSWER-Low E, High a, Low Tm
The number of vacancies in a crystal ____ as temperature increases - ANSWER-
increases
T/F: some materials will experience a transition from ductile to brittle fracture with a
decrease in temperature? - ANSWER-True
Why do ceramics generally have a higher melting temperature than metals? -
ANSWER-Ceramics generally have stronger bongs than metals
A line of distorted or incomplete bonds in a crystal describes a ____________ -
ANSWER-dislocation
Why does a metal expand when heated? - ANSWER-The asymmetry in the atomic
bonding potential curve causes the atoms to move farther apart on average when their
energy increases.
Rank density of classes of materials from lowest to highest - ANSWER-
polymers<ceramics<metals
(C2F4)n has which types of bonding? - ANSWER-Covalent and secondary
Amorphous glasses tend to be more or less dense than their crystalline counterparts? -
ANSWER-less
Why is dislocation slip difficult in ceramic materials? - ANSWER-Because bonding in
ceramics can be directional and for dislocations to move in ceramics ions with like
charges could be required to move closer to each other
