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IUB CHEM-C 118 - 10-24 chapter 11

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Clicker Question11: Solids and MaterialsClicker Question11.7 Network Solids11.8 Materials ScienceMaterials Science11.9 MetalsMetalsElectrons in Metals–BondingBand TheoryElectrons in Metals, Semiconductors & InsulatorsElectrons in Metals, Semiconductors & InsulatorsSuperconductorsSuperconductorsSuperconductorsClicker QuestionSilicon & the ChipSilicon & the ChipSilicon & the ChipSilicon & the ChipClicker QuestionIdentify the following type of solid:A brittle yellow solid that melts at 113 °C; neither the solid nor the liquid conducts electricityA. Molecular bp is not very high, can knock out because of weak IMF B. Metallic metals (as solids = good metal conductors) C. Ionic-> liquid conducts electricityD. NetworkE. Amorphous broad melting points11: Solids and Materials11.5 Types of Solids11.6 Crystalline Solids11.7 Network Solids11.8 Materials Science11.9 Metals, Semiconductors, and Insulators11.10 Silicon and the Chip11.11 Cement, Ceramics and GlassFriday, October 24, 2014Read: Sections 11.7 – 11.9 for FridaySections 11.9 – 11.11 for MondayEnd of Chapter 11 Problems: 59, 61, 63, 65, 72, 75, 77, 84, 86, 88, 90, 92, 93, 108Friday, October 24, 2014Read: Sections 11.7 – 11.9 for FridaySections 11.9 – 11.11 for MondayEnd of Chapter 11 Problems: 59, 61, 63, 65, 72, 75, 77, 84, 86, 88, 90, 92, 93, 108Clicker QuestionUsing the NaCl structure shown, how many unit cells share each of the Na+ ions in the front face of the cell?A. 2B. 4C. 6D. 811.7 Network SolidsSome non-metals link together in extended networks. DiamondGraphiteHard, insulator Soft, conductor11.8 Materials ScienceStudy of the relationships between the structure and the chemical and physical properties of materials.Four major classes of materials:2. Polymers •Natural•Synthetic(Usually) thermal and electrical insulators.1. MetalsMaterials Science3. Ceramics•Nonmetallic.•Often clay based.•Poor thermal conductors.•Good electrical insulators. •Often crystalline.4. Composites •Combinations of the 3 other materials.•Properties exceed those of the components.11.9 MetalsMetals are:•Opaque, shiny, usually crystalline and form alloys.•Ductile and malleable.•Mostly nonmagnetic (exceptions iron, nickel)•Insoluble in water and other common solvents.•Silvery-white (fairly non color)They have:•High electrical conductivity.•High thermal conductivity.ΔHfusMetalsMetal ΔHfus mp(kJ/mol) (°C)Hg 2.3 –38.8Ga 7.5 29.8Na 2.6 97.9Li 3.0 180.5Al 10.7 660.4U 12.6 1132.1Fe 13.8 1535.0Ti 20.9 1660.1Cr 16.9 1857.0W 35.2 3410.1ΔHfus (and mp) vary widely:Metallic bonding = Nondirectional attraction between M+ and a sea of mobile valence e–.Valence e– spread throughoutthe M+ lattice, holding the M+ ions together.Electrons in Metals–BondingAn electric field can pull valence e– to a “+” electrodeM+ can move without destroying M+ ~ e– attractions for ductility and malleability – not true for other solidsBand TheoryEvery atom has E-levels (s, p, d…).As multiple atoms come together orbitals interact.1Number ofatomse- inatomse- in latticeenergy levels3212manyfilledemptyBand TheoryThe valence band (VB) contains the valence e–.Electrons in Metals, Semiconductors & Insulators1Number ofatomse- inatomse- in latticeenergy levels3212manyfilledemptyHigher-E orbitals form the conduction band (CB)In a metal, the valence and conduction band overlap.e– can move freely between bands.band gapinsulatorsemi-conductorconductorMetalBands overlap•Lots of open levelsInsulatorLarge band gap•e– cannot jump the gapSemiconductorNarrow band gap.•Some e– can jump the gap…Electrons in Metals, Semiconductors & InsulatorsMetals are better conductors at low T.Superconductors have zero resistance at some (low) T.typical metalResistanceTemperature (K)superconductorTccritical T0SuperconductorsMetal Tc (K)Gallium 1.10Aluminum 1.15Tin 3.72Mercury 4.15Lanthanum 4.9Lead 7.2Several metals are superconductors at low TNb3Sn alloy 18.1YBa2Cu3O7 90.LaBa2Cu3Ox 35.He(ℓ) boils at 4.2 KMany He(ℓ)-cooled magnets use Nb-alloys1st ceramic superconductor (1986).N2(ℓ) boils at 77 K“Y123” found 4 months later.Highest Tc so far…Hg0.8Tl0.2Ba2Ca2Cu3O8.23 138.Some alloys are better…SuperconductorsWhy the excitement?•Better magnets.•Loss free electrical transmission.•MaglevSuperconductorsShanghai maglev trainLevitation of a magnet above asuperconductorClicker QuestionIdentify the following type of solid:A soft, silvery solid that melts at 40 °C; both the solid and the liquid conduct electricity.A. MolecularB. MetallicC. Ionic- solid don’t conduct electricityD. NetworkE. Amorphous- metalsSilicon & the ChipControlled addition of another element.Silicon & the ChipA p-n junction.Charge carriers: holes (p-type) and e– (n-type)Silicon & the ChipSmart chips:•Can we diagnose a disease with a single chip?•Example: Systemic Lupus Erythematosus (SLE)•May provide in situ disease diagnosis and observation in real-timeNature Medcine. 2012; 18 (9): 1434Silicon & the ChipA photovoltaic cell.


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