Quiz 1 Flashcards
subatomic structure
electrons within the individual
atoms, their energies and interactions with nuclei
atomic structure
relates to the organization of
atoms to yield molecules or crystals
nanostructure
atoms that form particles
(nanoparticles) that have nanoscale dimensions
(<100 nm)
microstructure
structural elements observed with
microscope
macrostructure
structural elements seen with naked eye
metal material type
-strong, ductile
-high thermal and electrical conductivities
-opaque, reflective
polymer/plastic material type: compounds of non-metals
− Soft, ductile, low strengths, low densities
− Low thermal & electrical conductivities
− Opaque, translucent or transparent
ceramic material type: compounds of metallic & non-metallic
elements (oxides, carbides, nitrides, sulfides)
− Hard, Brittle
− Low thermal & electrical conductivities
− Opaque, translucent, or transparent
mechanical properties
relate deformation to an applied load or force (ex. strength, resistance to fracture)
electrical properties
stimulus is an applied electric field (ex. conductivity, dielectric constant, resistivity)
thermal properties
related to changes in a temperature or temperature gradients across a material (ex. heat capacity, thermal expansion, thermal conductivity)
magnetic properties
responses of a material to application of a magnetic field (ex. magnetic susceptibility, permiability)
optical properties
stimulus is electromagnetic or light radiation (ex. reflectivity, index of refraction)
-single crystal typically optically transparent, whereas polycrystalline can be translucent or opaque
deteriorative properties
chemical reactivity of materials (ex. corrosion resistance)
advanced materials
semiconductors, biomaterials, smart materials, nanomaterials
Avogadro’s Number
1 mol = 6.022 x 10^23 atoms or molecules
What properties are determined by atomic structure?
chemical, electrical, thermal, optical
How do you calculate average atomic mass?
average mass = m1p1 + m2p2
Which of the following is the best example of a
material property?
(a) Density
(b) Annealing
(c) Forging
(d) Single-crystal
(e) Crystalline
a) Density
Which of the following is the best example of
material processing?
(a) Extrusion
(b) Crystalline
(c) Amorphous
(d) Glassy
(e) Elastic Modulus
a) Extrusion
Which of the following is the best example of
material structure?
(a) Single-phase
(b) Elastic Modulus
(c) Sintering
(d) Magnetic Permeability
(e) Brittle
a) single-phase
Which class of material is generally associated with
the highest density values at room temperature?
(a) Composites
(b) Ceramics
(c) Metals
(d) Polymers
c) metals
Ionic Bonds
- metal donates e- and nonmetal accepts e-
- requires large EN difference
ex. NaCl
Covalent Bonding
- Share valence electrons to fill shell
- Similar ENs
Metallic Bonding
electrons delocalized to form an “electron cloud”
Primitive Unit Cell
Just one atom per unit cell (1 lattice point total)
coordination number
number of nearest neighbors of an atom in a unit cell system
Simple Cubic APF
0.52
APF of BCC
0.68
APF of FCC and HCP
0.74
Coord Number of SC
6
Coord Number of BCC
8
Coord Number of FCC and HCP
12
BCC Packing Direction parameter
4r=sqrt(3)a
FCC Packing Direction parameter
4r=sqrt(2)a
How many atoms in SC unit cell?
1 atom
How many atoms in FCC unit cell?
4
How many atoms in BCC unit cell?
2
isotropic
for polycrystalline materials having randomly oriented grains, properties are independent of
crystallographic orientation
anisotropic
For most single crystals, properties vary with crystallographic orientation
