MTL 200 2025 EXAM QUESTIONS AND 100%
CORRECT ANSWERS!!
What is an isotope?
Atoms of the same element that have different numbers of neutrons
What is the Pauli Exclusion Principle?
each electron state can hold no more than two electrons which must have opposite signs
What is the Stable Electron Configuration?
the state within the outermost shell completely filled (ex. inert gases: He, Ne, Ar, etc)
What is bonding energy?
the energy required to separate two atoms that are chemically bonded to an infinite distance
(units: kJ/mol or eV/atom)
Which kinds of bonds are nondirectional? Which are directional?
Nondirectional: ionic bonding, metallic bonding
Directional: covalent bonding
What is the difference between directional and nondirectional bonding?
Nondirectional: magnitude of the bond is equal in all directions around an ion
Directional: atoms need to be in a specific orientation
What is the relationship between the unit cell edge length and the atomic radius for FCC
crystal structures?
a = unit cell edge length
R = atomic radius
a = 2Rsqrt(2)
How many atoms are in the FCC structure?
4 atoms
,What is the relationship between the unit cell edge length and the atomic radius for BCC
crystal structures?
a = (4R)/sqrt(3)
How many atoms are in the BCC structure?
2 atoms
What is the relationship between the unit cell edge length and the atomic radius for HCP
crystal structures?
a = 2R
How many atoms are in the HCP structure?
6 atoms
What is the formula for volume of HCP unit cell in terms of a and c?
V = (3ca^2sqrt(3))/2
What are the coordination numbers of FCC, BCC, and HCP structures?
FCC: 12
BCC: 8
HCP: 12
What are the APF of FCC, BCC, and HCP structures?
FCC: 0.74 or 74%
BCC: 0.68 or 68%
HCP: 0.74 or 74%
What is the formula for the volume of 4 atoms in FCC?
V=4*(4/3)(piR^3)
What is polymorphism? What is it called for elements?
- the phenomenon of a solid material existing in more than one form of crystal structure.
- for elements, it is called allotropy
, What coordinate form do you use for crystallographic directions for cubic structures,
hexagonal structures and for a family of equivalent directions?
Cubic structures: [UVW]
Hexagonal structures: [uvtw]
Family of equivalent directions: <uvw> <uvtw>
How do you convert [UVW] to [uvtw]?
u = (1/3)(2U-V)
v = (1/3)(2V-U)
t = -(u+v)
w=W
What is the formula for linear density (LD)?
LD = (# of atoms centered on a direction vector)/(length of direction vector)
What kind of brackets are used for linear? ( ) or [ ]?
[]
What is the formula for planar density? (PD)
PD = (# of atoms centered on a plane)/(area of a plane)
What kind of brackets are used for planar? ( ) or [ ]?
()
What is anisotropy?
material properties are DEPENDENT on orientation
What is isotropic?
material properties are INDEPENDENT of specimen orientation
Given the crystal structure, what are the reflections present (RP)?
BCC
CORRECT ANSWERS!!
What is an isotope?
Atoms of the same element that have different numbers of neutrons
What is the Pauli Exclusion Principle?
each electron state can hold no more than two electrons which must have opposite signs
What is the Stable Electron Configuration?
the state within the outermost shell completely filled (ex. inert gases: He, Ne, Ar, etc)
What is bonding energy?
the energy required to separate two atoms that are chemically bonded to an infinite distance
(units: kJ/mol or eV/atom)
Which kinds of bonds are nondirectional? Which are directional?
Nondirectional: ionic bonding, metallic bonding
Directional: covalent bonding
What is the difference between directional and nondirectional bonding?
Nondirectional: magnitude of the bond is equal in all directions around an ion
Directional: atoms need to be in a specific orientation
What is the relationship between the unit cell edge length and the atomic radius for FCC
crystal structures?
a = unit cell edge length
R = atomic radius
a = 2Rsqrt(2)
How many atoms are in the FCC structure?
4 atoms
,What is the relationship between the unit cell edge length and the atomic radius for BCC
crystal structures?
a = (4R)/sqrt(3)
How many atoms are in the BCC structure?
2 atoms
What is the relationship between the unit cell edge length and the atomic radius for HCP
crystal structures?
a = 2R
How many atoms are in the HCP structure?
6 atoms
What is the formula for volume of HCP unit cell in terms of a and c?
V = (3ca^2sqrt(3))/2
What are the coordination numbers of FCC, BCC, and HCP structures?
FCC: 12
BCC: 8
HCP: 12
What are the APF of FCC, BCC, and HCP structures?
FCC: 0.74 or 74%
BCC: 0.68 or 68%
HCP: 0.74 or 74%
What is the formula for the volume of 4 atoms in FCC?
V=4*(4/3)(piR^3)
What is polymorphism? What is it called for elements?
- the phenomenon of a solid material existing in more than one form of crystal structure.
- for elements, it is called allotropy
, What coordinate form do you use for crystallographic directions for cubic structures,
hexagonal structures and for a family of equivalent directions?
Cubic structures: [UVW]
Hexagonal structures: [uvtw]
Family of equivalent directions: <uvw> <uvtw>
How do you convert [UVW] to [uvtw]?
u = (1/3)(2U-V)
v = (1/3)(2V-U)
t = -(u+v)
w=W
What is the formula for linear density (LD)?
LD = (# of atoms centered on a direction vector)/(length of direction vector)
What kind of brackets are used for linear? ( ) or [ ]?
[]
What is the formula for planar density? (PD)
PD = (# of atoms centered on a plane)/(area of a plane)
What kind of brackets are used for planar? ( ) or [ ]?
()
What is anisotropy?
material properties are DEPENDENT on orientation
What is isotropic?
material properties are INDEPENDENT of specimen orientation
Given the crystal structure, what are the reflections present (RP)?
BCC
