Lattice points occupied by metal atoms held together

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Lattice points occupied by metal atoms Held together by metallic bonds Soft to hard, low to high melting point Good conductors of heat and electricity Cross Section of a Metallic Crystal nucleus & inner shell e - mobile “sea” of e -
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Crystal Structures of Metals
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Types of Crystals
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An amorphous solid does not possess a well-defined arrangement and long-range molecular order. A glass is an optically transparent fusion product of inorganic materials that has cooled to a rigid state without crystallizing Crystalline quartz (SiO 2 ) Non-crystalline quartz glass
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The band of molecular orbitals in lithium metal.
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Electrical conductivity in a conductor, semiconductor, and an insulator.
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Chemistry In Action: High-Temperature Superconductors
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Chemistry In Action: And All for the Want of a Button white tin grey tin T < 13 0 C stable weak two allotropes of tin
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Phase Changes – An Introduction If you ↑Temp, then you ↑KE, so that average KE of particle motion > PE of electrostatic attraction vaporization and melting If you ↓Temp, then you ↓KE, so that PE of electrostatic attraction > average KE of particle motion condensation and freezing * This interplay between average KE of particle motion (directly related to temperature) and PE of electrostatic attraction between particles is at the heart of phase changes . Phase changes are accompanied by enthalpy changes ( Δ H) , which can either be exothermic (condensing and freezing, or deposition**) or endothermic (melting and vaporization, or sublimation**) (example: when you sweat, the endothermic evaporation of the sweat involves a heat transfer from your body for the purpose of vaporization of the water in sweat, which leads to a cooling effect to the body) During phase changes, there are stages involving system temperature change (cooling or heating stages), and stages involving no system temperature change (phase-equilibrium stages). We will use heating/cooling curves to investigate this kinetic-molecular approach to phase changes. *don’t always relate the word “freezing” to “cold” temperatures from our own point of view – it merely means a phase change from liquid to solid at ANY temperature – it is referred to as “fusion” ** sublimation refers to a phase change from a solid to a gas, bypassing the liquid phase; deposition refers to a phase change from a gas to a solid, bypassing the liquid phase
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Evaporation Greatest Order Least Order Condensation T 2 > T 1
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Equilibrium Nature of Phase Changes In closed systems under controlled conditions, phase changes of many substances are reversible and reach a dynamic equilibrium, during which the temperature remains constant : Liquid-Gas Equilibria rate of vaporization = rate of condensation The pressure exerted by gas vapor at this equilibrium is called the equilibrium vapor pressure of the liquid at that temperature (qualitatively referred to as a substance’s “volatility”) Solid-Liquid Equilibria rate of melting = rate of freezing Solid-Gas Equilibria rate of sublimation = rate of deposition
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The
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