KMT_page3 - PHASE CHANGES • Transformations from one...

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Intermolecular Forces and Liquids and Solids CHM12 ., < . . CRYSTAL STRUCTURE OF SOLIDS o Metallic crystals: array of positive ions immersed in a sea of delocalized valence electrons 1. CRYSTALLINE: possesses rigid and long range order. Its atoms, molecules or ions occupy specific positions. Atoms, ions are arranged such that the net attractive intermolecular forces are at their maximum. Forces present: ionic forces, covalent bonds, van der waals, hydrogen bonds or combinations. Types of crystals according to forces between particles o Ionic crystals: have high melting point and do not conduct electricity. Why? 2. Amorphous solids: does not possess a well defined arrangement and long range molecular order ( example: glass) ! EEORDONO Page 3 o Molecular crystals: atoms or molecules are held together by Van der Waals forces and/or H bonding. This crystal can easily be broken. Why?
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Unformatted text preview: PHASE CHANGES • Transformations from one phase to another occur when energy is added or removed • Physical changes characterized by changes in molecular order 1. Liquid- Vapor Equilibrium a. Vapor Pressure: exerted by gaseous molecules as liquid evaporates • Dynamic equilibrium: rate of evaporation = rate of condensation • Equilibrium Vapor Pressure: vapour pressure measured when dynamic equilibrium exists between condensation and evaporation. • Inc vapour pressure •• increase temperature b. Molar Heat of Vaporization: is the energy required to vaporize 1 mole of a liquid. • Inc IMF •• Inc Heat of Vaporization - dec Vapor pressure o Covalent Crystals: atoms are held together entirely by covalent bonds in an extensive 3-~ network....
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This note was uploaded on 10/19/2011 for the course CHEM 12 taught by Professor Ma'amordono during the Summer '11 term at Mapúa Institute of Technology.

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