Exam 1 Flashcards
Q: What are the steps in the Materials Selection Process?
A:
Pick Application: Determine required properties.
Identify candidate material(s) based on properties.
Identify required processing for the chosen material.
What are some examples of material processing methods?
A: Casting, sintering, vapor deposition, doping, forming, joining, annealing.
Q: What are the main properties to consider when selecting materials?
A: Mechanical, electrical, thermal, magnetic, optical, deteriorative.
Q: What are the key characteristics of metals?
A:
Strong, ductile.
High thermal & electrical conductivity.
Opaque, reflective
Q: What are the key characteristics of polymers/plastics?
A:
Soft, ductile, low strength, low density.
Thermal & electrical insulators.
Optically translucent or transparent.
Q: What are the key characteristics of ceramics?
A:
Brittle, glassy.
Non-conducting (insulators).
Ionic bonding (refractory), compounds of metallic & non-metallic elements.
Q: What is the atomic number (Z) of an element?
A: The number of protons in the nucleus, and also the number of electrons in a neutral species.
Q: What is the formula for atomic mass?
A: Atomic mass = Protons + Neutrons = Atomic mass unit (amu), where 1 amu is 1/12th the mass of Carbon-12.
Q: How many atoms or molecules are in one mole of a substance?
A: 6.022 x 10²³ (Avogadro’s number).
Q: What do electron energy states represent?
A: energy level. the 3-dimensional space surrounding the nucleus where electrons are most likely to be, tend to occupy the lowest available energy state.
Q: What are the quantum numbers that describe an electron’s state?
A:
Principal (n): Energy level (shells).
Subsidiary (l): Orbital shape.
Magnetic (ml): Orbital orientation.
Spin (ms): Spin of the electron (±½).
Q: What dual properties do electrons have?
A: Electrons have both wavelike and particulate properties.
Q: What are two wavelike characteristics of electrons?
A:
Electrons are in orbitals defined by a probability.
Each orbital exists at a discrete energy level determined by quantum numbers.
Interference
When two electron waves meet, they can overlap and create a new wave pattern.
Diffraction
When an electron wave passes through a small opening, it bends around the edges of the opening
Q: Why is the electron configuration of most elements not stable?
A: The valence (outer) shell is usually not completely filled, making the electron configuration unstable.
Q: What are valence electrons?
A: Valence electrons are the electrons in unfilled shells, available for bonding, and they control the chemical properties of the element.
Q: What is a key characteristic of elements in the same column of the Periodic Table?
A: Elements in the same column have similar valence structures.
Q: What is the difference between electropositive and electronegative elements?
Electropositive elements readily give up electrons to become positive ions.
Electronegative elements readily acquire electrons to become negative ions.
Ionic bonding is the “ “ of electrons
transfer, with +- electrons
Q: What factors determine the physical properties of materials?
A: The interatomic forces between atoms, which are influenced by temperature and pressure.
Q: What are the types of primary bonding?
A: Metallic bonding, ionic bonding, covalent bonding.
Q: What is secondary bonding, and what is an example?
A: Secondary bonding refers to weaker forces like Van der Waals bonding.
Q: What is ionic bonding and between which types of atoms does it occur?
A: Ionic bonding occurs between a metal and a non-metal, where the metal donates electrons and the non-metal accepts them. It requires a large difference in electronegativity.
Q: ionic bonding predominant in ceramics T/F?
A: T. Ionic bonding is predominant in ceramics.
Q: How does the coefficient of thermal expansion, α, relate to the bonding energy, E₀?
A: A larger α (thermal expansion) corresponds to a smaller E₀ (bonding energy).
