Bonding
Do stronger bonds lead to higher or lower thermal expansion?
What is the crystal structure of aluminum?
FCC
What two types of bonds can be found in ceramics?
Ionic and covalent
What is a single unit of a polymer called?
Monomer
What is the most abundant element in the universe?
Hydrogen
What types of bonds exist in graphite?
Covalent and van der Waals
What is the atomic packing factor of a BCC crystal?
.68
What type of defect consists of a cation vacancy-interstitial pair?
Frenkel defect
Name two types of intermolecular forces that act between polymer chains.
Hydrogen bonding, van der Waals forces, dipole-dipole interactions
What is the traditional order of the materials tetrahedron?
Processing, structure, properties, performance
Of the primary bond types, which are the most directional bonds?
Covalent
What are the two primary elements in Sterling silver?
Silver and copper
Name one tissue or organ of the human body that contains the mineral hydroxyapatite.
Bones or teeth
In rubber vulcanization, what element is primarily responsible for forming crosslinks between polymer chains?
Sulfur
How much carbon is in 1040 steel? (1 sig fig needed)
.4 wt%
What is the coordination number of an FCC crystal?
12
Why are metals more ductile than ceramics?
Slip systems allow dislocations to move, enabling plastic deformation before fracture
Which element, when added to GaN, allows for the creation of a blue LED?
Indium
What is the difference between thermoplastics, thermosets, and elastomers?
Thermoplastics: linear or branched chains, flow at high temperatures
Thermosets: highly crosslinked, degrade at high temperatures
Elastomers: moderate crosslinking allows chains to uncoil under load, degrade rather than melt
What element is primarily responsible for the green color in emeralds?
Chromium
What equation describes a model for simple intermolecular interactions between two atoms based on the distance between them?
Hint: The exponent on the repulsive term is -12 and on the attractive term is -6.
Lennard-Jones potential
Define recovery, recrystallization, and grain growth.
Recovery: dislocations move to relieve some of the material's internal strain energy
Recrystallization: new, strain-free grains nucleate and grow, consuming original grains
Grain growth: larger grains grow at the expense of smaller grains
Explain one reason why is glass transparent to visible light.
Amorphous structure allows light to pass without interacting with grain boundaries.
Wide bandgap absorbs only higher energy (shorter frequency) light, like UV.
List the polymers corresponding to recycling numbers 1-7.
1=PET/PETE, 2=HDPE, 3=PVC
4=LDPE, 5=PP, 6=PS
7: other
What is the elastic modulus of tungsten? (1 sig fig needed)
400 GPa