Materials Engineering Exam 1

properties of metals

- Dense, stiff, and strong but ductile - High resistance to fracture - Good conductors of electricity and heat

properties of composites

-Combine other types of materials -Tailor material properties for specific uses -Properties can differ based on fiber direction

properties of polymers

-Extremely ductile and pliable -Generally inert and unreactive -Soften at modest temperature

properties of ceramics

-Hard, stiff, and strong -Brittle and susceptible to fracture -Good insulators of electricity and heat

There is (are) ___ 2sp^2 hybrid orbital(s) present in each sp^2 hybridized carbon atom

3

define biomaterial

A biomaterial is a nonliving material implanted into the body. A biomaterial must be reliable, safe, and compatible with body tissues and fluids. Ex: Hip and knee replacements, heart valves

define nanomaterials

A nanomaterial has structural elements less than 100 nanometers. The atoms can be arranged to customize material properties. Ex: Carbon nanotubes, graphene, and nanocomposites

Pauli exclusion principle

An atomic orbital may have at most two electrons, each with opposite spin direction

What atomic model does this describe: Electrons are assumed to revolve around the nucleus in discrete orbitals

Bohr Atomic model In the Bohr model, the position of any particular electron is well defined in terms of orbitals.

what primary bonding type does the following describe: The mixing of two or more atomic orbitals

Bond hybridization it occurs when an electron moves to a different orbital and creates equivalent hybrid orbitals.

The _____ for two atoms represents the energy required to separate the two atoms to an infinite separation.

Bonding energy The bonding energy, E0, is the minimum on the net potential energy curve on a graph of the potential energy versus interatomic separation. E0 occurs at an interatomic separation r0.

aluminum oxide is a type of what material

Ceramic Aluminum oxide has a metallic element, aluminum, and nonmetallic element, oxygen.

how would you improve the following stress contribution in a ship sinking: inexperienced welders created weld defects

Improved welding practices and codes Improving welding practices and welding codes reduced the weld defects and discontinuities.

define quantum numbers

In wave mechanics, every electron in an atom is characterized by four parameters called quantum numbers The size, shape, and spatial orientation of an electron

how would you improve the following stress contribution in a ship sinking: cracks propagated through welded steel sheets

Installed riveted straps and strong weld seams Riveted straps and strong weld seams stop cracks from propagating.

how would you improve the following stress contribution in a ship sinking: ductile to brittle transition in cold water

Lowered the steel's ductile-to-brittle transition temperature The ductile-to-brittle transition temperature was lowered by increasing the steel's quality. Correct

high carbon steel is a type of what material

Metal High carbon steel has a metallic material, iron, and a small amount of a nonmetallic material, carbon.

metals definition

Metals are composed of one or more metallic elements (e.g., iron, aluminum, copper, titanium, gold, nickel), and often also nonmetallic elements (e.g., carbon, nitrogen, oxygen) in relatively small amounts.

High Density Polyethylene (HDPE) is a type of what material

Polymer High density polyethylene (HDPE) is a chainlike organic compound of carbon and hydrogen.

polymers definition

Polymers include the familiar plastic and rubber materials. Many of them are organic compounds that are chemically based on carbon, hydrogen, and other nonmetallic elements (i.e., O, N, and Si). Furthermore, they have very large molecular structures, often chainlike in nature, that often have a backbone of carbon atoms. example: polyethylene (PE), nylon, poly(vinyl chloride) (PVC), polycarbonate (PC

define quantum mechanics

Principles and laws that govern atomic and subatomic entities Quantum mechanics involves the study of the behavior of electrons in atoms that could not be explained by classical mechanics.

Improvements in material _____ are needed to control water and air pollution.

Processing Material processing and refinement need to produce less pollution, less impact on the land, and fewer toxic substances.

thermal properties

Relate to changes in temperature or temperature gradients across a material Ex: Thermal expansion and heat capacity

mechanical properties

Relate to deformation in response to an applied load or force Ex: Elastic modulus, strength, and resistance to fracture

deteriorative characteristics

Relate to the chemical reactivity of materials Ex: Corrosion resistance of metals

the third quantum number represents what

Relates to an orbital's energy state when a magnetic field is applied 1 < ml < 1 The magnetic quantum number, ml describes an orbital's change in energy state when a magnetic field is applied and can have values between −1 and 1

how would you improve the following stress contribution in a ship sinking: stress concentrations at corners

Rounded off hatch corners Rounding the hatch corners by welding a curved reinforcement strip reduced the stress concentrations.

what improvements need to be made to solar and nuclear energy to make them usable for transportation?

Solar cells will need a more efficient energy conversion process, lower cost materials, and improved energy storage capacity of batteries. Nuclear energy needs new fuels, better materials for containment structures, and better materials for radioactive waste disposal facilities.

magnetic properties

The responses of a material to the application of a magnetic field Ex: Magnetic susceptibility and magnetization

electrical properties

The stimulus is an applied electric field Ex: Electrical conductivity and dielectric constant

optical properties

The stimulus is electromagnetic or light radiation Ex: Index of refraction and reflectivity

What atomic model does this describe: Electrons have a probability of being at various locations around the nucleus

Wave-mechanical model In the wave-mechanical model, the position of an electron is described by a probability distribution.

Electronegativity

a measure of how (un)willing atoms are to accept electrons

Sodium (Na) is classified as a(n) _____. alkaline earth metal alkali metal transition metal

alkali metal Elements in column 1 (H, Li, Na, K, Rb, Cs, Fr) are considered alkali metals.

All _____ must be compatible with body tissues and fluids.

biomaterials

Bonding energy depends on the atom types involved in the bond and the material's_____.

bonding type Bonding energy depends on the atom types involved in the bond and the bonding type. Some types of bonds have much higher bonding energies than other types of bonds.

Covalent bonding occurs between atoms that are _____ the periodic table.

close together in Atoms that are close together in the periodic table have a similar electronegativity and tend to form covalent bonds.

composites definition

composed of two (or more) individual materials that come from the categories previously discussed—metals, ceramics, and polymers example: fiberglass

Carbon Fiber Reinforced Polymers (CFRP) is a type of what material

composite Carbon fiber-reinforced polymer is a composite of carbon fibers inside a polymer.

ceramics definition

compounds between metallic and nonmetallic elements; they are most frequently oxides, nitrides, and carbides. For example, common ceramic materials include aluminum oxide (or alumina, Al2O3), silicon dioxide (or silica, SiO2), silicon carbide (SiC), silicon nitride (Si3N4)

The free valence electrons in metallic solids cause metallic solids to be good _____ of electricity.

conductors

what primary bonding type does the following describe: Two elements with similar electronegativity share at least one electron each

covalent bonding A covalent bond is formed by two atoms sharing electrons. The shared electrons belong to both atoms.

nanostructure

deals with groups of atoms that form very small particles.

thermal conductivity ___ when you add impurities atoms and grain boundaries

decreases

A covalent bond is _____

directional A covalent bond can only exist in the direction between the atoms that share electrons.

subatomic structure

electrons within atoms.

The _____ of the carbon-12 isotope represents the amount of carbon-12 in relation to the amount of all isotopes of carbon.

fraction of occurrence The fraction of occurrence represents the amount of a particular isotope in relation to the amount of all isotopes of an element.

Valence electrons in metallic bonds are ___

free to move throughout the metallic solid

A metallic atom tends to _____ electrons to have a filled outer electron shell.

give up A metallic atom is electropositive and tends to give up the few valence electrons.

Iodine (I) is classified as a(n) _____.

halogen Elements in column 17 (F, Cl, I, Br, I, At) are classified as halogens.

define semiconductor

have electrical properties that are intermediate between those of electrical conductors (i.e., metals and metal alloys) and insulators (i.e., ceramics and polymers) covalent bonding Ex: Integrated circuits (microchips) for electronics and computers

do subshells with one missing electron have low or high electronegativity

high

Solids at room temperature typically have _____ bonding energies.

high Solids at room temperature typically have high bonding energy. High bonding energy results in a melting temperature much higher than room temperature.

Bond hybridization can occur ____

in some elements Although bond hybridization is most often associated with carbon, it can occur in some other nonmetals and transition metals.

Increasing the bonding energy will _____ the stiffness of a material.

increase Increasing the bonding energy will increase the stiffness of a material. Higher bonding energy means that the bonds between atoms are more difficult to break.

Electronegativity trend on the periodic table

increases from left right

Krypton (Kr) is classified as a(n) _____

inert gas Elements in column 18 (He, Ne, Ar, Kr, Xe, Rn) on the periodic table shown above are called inert gases.

The availability of _____ was key to the automobile's development.

inexpensive steel

silicon is an example of what type of element

intermediate Silicon is classified as intermediate based on chemical and physical properties that are similar to both metals and nonmetals.

do subshells with one electron have low or high electronegativity

low

Understanding the relationships between _____ and material properties allows scientists to create new materials with better properties.

material structure

Ionic bonding occurs between _____.

metals and nonmetals

sulfur is an example of what type of element

nonmetal

A coulombic force of attraction is found in ionic bonding when two ions have _____ charges.

opposite An opposite charge causes an attractive force that results in an ionic bond.

An ion core composed of the atom's nucleus and remaining nonvalence electrons has a _____ charge.

positive

paradigm of materials engineering put the following in order structure, properties, processing, performance

processing > structure > properties > performance A material's structure depends on how the material was processed. Ex: A metal's microstructure depends on the metal's fabrication and processing. A material's properties depend on the structure. Ex: A ceramic's optical properties depend on electronic structure. A material's performance depends on the properties. Ex: The aluminum alloy for an orchard ladder must have adequate strength and stiffness.

A nonmetallic atom tends to _____ electrons to have a filled outer electron shell.

receive A nonmetallic atom is electronegative and tends to receive a small number of valence electrons to fill the outer electron shell.

Developing _____ will reduce the world's dependence on nonrenewable materials.

renewable materials with similar properties Developing renewable materials with similar properties to the nonrenewable materials that are currently used will reduce the world's dependence on nonrenewable materials.

All _____ have electrical properties between an electrical conductor and an electrical insulator.

semi conductors

The development of sophisticated electronic devices was a result of _____.

semiconducting materials

Covalent bonding occurs when two atoms _____ electrons

share

the first quantum number represents what

size n = size of electron orbital

A _____ uses sensors and actuators to change a material's characteristics in response to environmental changes.

smart material

define smart materials

smart material uses a sensor and actuator to adapt to environmental changes. Ex: Smart helicopter rotor blades reduce cockpit noise using sensors and noise-canceling

Bond hybridization in carbon can take the form of _____ hybrid bonds

sp^2 and sp^3

the fourth quantum number represents what

spin orientation ms can equal -1/2 or 1/2

what are the four steps of the material selection process cycle

step 1: in-service conditions step 2: trade off material properties step 3: deterioration of material properties step 4: economical material and fabrication

macrostructure

structural elements that can be seen with the naked eye.

microstructure

structural elements that can only be seen using a microscope.

the second quantum number represents what

subshell shape l = s(0), p(1), d(2), f(3)

A material scientist must consider _____ of a material when choosing a material for a particular application.

the entire life cycle A material scientist must consider the entire life cycle of a material including processing, performance, and recyclability when choosing a material.

What is true of the energy-distance curves near equilibrium for two materials with different thermal expansion coefficients?

the material with the lower thermal expansion coefficient has a steeper slope and more negative value

atomic structure

the organization of atoms that make molecules or crystals.

Ionic bonding occurs when electrons belonging to two different atoms are ____

transferred atoms transfer electrons, either giving or receiving, in ionic bonding to have filled outer electron shells.

Uranium (U) is classified as a(n) _____.

transition metal Uranium (U) is a part of the actinide series at the bottom of the periodic table but is still considered a transition metal.