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62 Cards in this Set
- Front
- Back
Number of Elements |
100+ elements, 87 known metals |
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Structure |
Relates to the arrangement of a materials internal components |
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Density formula |
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Transparency indicates what kind of crystal structure? |
Completely See through - Single Crystal |
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Translucent appearance indicates what kind of crystal structure? |
Polycrystalline - partly see through |
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Opaque appearance indicates what kind of crystal structure? |
Polycrystalline with porosity - not see through |
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A-iron: name, structure and formation temperature |
Ferrite, forms below 910°C, BCC |
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Gamma iron: Name, formation temperature and Crystal structure |
Austenite, forms above 910°C up to 1,400°C, FCC |
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What are metals? |
Comprised of one or more metallic elements (eg Fe, Al, Cu, Ti, Au and Ni) and small amounts of non-metallic elements (C, N, O) Regular atomic arrangement Relatively dense relative to ceramics and polymers |
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Metals - Mechanical Properties |
Stiff Strong Ductile Fracture Resistant |
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Metals - Non-mechanical properties |
Free Electrons Good electrical and thermo conductor Desirable Magnetic properties |
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What are Ceramics? |
Oxides, Nitrides and Carbides |
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Ceramics - Mechanical Properties |
Stiff Strong Hard Brittle Engineered with improved fracture resistance |
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Ceramics - Other properties |
Insulating (heat and electrical) Can be Transparent, translucent or opaque Magnetic Behaviour |
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What are Polymers? |
Organic compounds based on C, H, and other non-metallic elements (eg O, N, Si) forming large chain like structures with backbone of C atoms. Plastic and Rubber materials |
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Examplea of Polymers |
Polyethalene (PE) Nylon Poly-vinyl-chloride (PVC) Polycarbonate (PC) Polystyrene (PS) Silicone Rubber |
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Polymers - Mechanical Properties |
Low Densities Ductile Plastic |
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Polymers - Other properties |
Chemically inert Tendency to soften/decompose Low electrical conductivity Non-magnetic |
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What are Composites and why are they made? |
Combinations of properties that are not displayed by a single material. To incorporate the best characteristics of each of the components materials |
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Synthetic composite examples |
Fiberglass Carbon Fiber-Reinforced Polymers (CFRP) |
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Natural Composite Examples |
Wood Bone |
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Mass of Proton/Neutron |
1.67 × 10^(-27) kg 1 amu |
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Mass of Electron |
9.11 × 10^(-31) kg |
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Charge of Proton & Electron |
Proton: + 1.602 × 10^(-19) C E: - 1.602 × 10^(-19) C |
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Atomic mass unit |
1 amu is defined as 1/12 of the atomic rest mass of C12 |
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Atomic Weight |
The weighted average of the masses of each naturally occurring isotope for a particular element. |
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Value of 1 mol |
6.022 × 10^23 |
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Bohr Model of the Atom |
Electrons have discrete orbital Electron energies are quantized (have specific energy levels/states) |
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Wave-Mechanical model of the atom |
Electron has both wave AND particle-like characteristics, position described by probability distribution (electron cloud). |
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What are the atomic quantum numbers? |
The four parameters to describe an electron: 1) Size of electrons probability density (electron cloud) 2) Shape of the electron cloud 3) Spatial Orientation of the cloud 4) Number of states within each subshell |
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The maximum number of subshells is.. |
..equivalent to the shell number n=1, 1 subshells possible n=2, 2 subshells possible |
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Each subshell can hold a maximum of.. |
4L+2 electrons |
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Electron energy levels: n &L |
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Atom is said to be in it's ground state when.. |
.. all the electrons occupy the lowest possible energy levels |
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What does Electron Configuration Describe? |
How Electrin states are occupied E.g. Hydrogen: 1s1 1s2 2s2 2p6 3s1 |
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Valence electrons |
Valence electrons occupy the outermost shell and are the only electrons to participate in bonding (hence define physical and chemical properties) |
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Interatomic seperation between two atoms net force graph. |
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Equilibrium spacing |
The distance (r0) between two atoms where the sum of the attractive and repulsive force (net force) is zero. (For many atoms, r0 ~~ 0.3 nm) |
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The dependence of net potential energies on interatomic separation for two isolated atoms graph. |
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Minimum in the net energy curve corresponds to what position. |
Equilibrium spacing - r0 |
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Bonding energy (E0) |
The energy required to separate the two atoms to infinity. |
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Large E0 (bonding energy) indicates.. |
..high melting temperature |
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Shape of interatomic separation curve indicates.. |
Elastic moduli |
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Linear coefficient of thermal expansion is related to the shape of what curve |
E0 - r0 curve |
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Types of Interatomic Bonding |
Ionic Covalent Metallic |
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Ionic bonding Constituents |
Always found in materials comprised of metallic AND non-metallic elements (eg. NaCl) |
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Ionic Bonding Mechanism |
Electrostatic forces between ions created by the donation and acceptance of a valence electron |
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Ionic Bonding properties |
Non-directional Predominant in ceramics High bind energies (600 to 1500 kJ/mol)( 3 to 8 eV) High melting temp Hard and Brittle Electrically and thermally insulating |
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Covalent Bonding constituents |
Non-metallic elements |
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Covalent Bonding Mechanism |
Atoms obtain a stable electron strucutre by sharing electrins between adjacent atoms, strength determined by electronegativity difference |
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Covalent Bonding Properties |
Directional bonding May be strong (eg. Diamond) and hard (MT >3550°C) or weak (Bismuth) (MT: 270°C) Found in Polymers |
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Metallic Bonding Constituents |
Metals |
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Metallic Bonding Mechanism |
Sea of electrons (drifting) unbound to each of the positively charged cores. |
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Metallic Bonding Properties |
Strong and weak bonds (0.7 eV for Hg or 8.8 eV for W) Good conductors |
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Secondary/Van Der Waals bonding arrises are a result of.. |
Atomic/Molecular dipoles |
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When do Dipoles exist |
When there is a separation between the positive and negative part of a atom/molecule (polar). Typically quite weak (0.1 eV) and arise due to Coulombic attraction. |
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Crystalline material |
A Crystalline material is one in which the atoms are situated in a repeating or periodic array over large atomic distances |
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Amorphous material |
A amorphous material is one in which the atoms are NOT situated in a repeating or periodic array over large atomic distances |
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Random vs. Regular Packing |
Dense, Regular Packing, is when the atoms are at equilibrium spacing/lowest potential energy |
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Crystal structure |
The way in which atoms, ions, or molecules are spatially arranged |
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Simple Cubic (SC) Properties |
Lattice Parameter = a = 2R Co-ordination Number = 6 Atoms/unit cell = 1 |
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Elements with Simple Cubic Structures |
Polonium (Po) |