1ChemistryChapter 14Central Science• Study of matter• Transformations it can make• Basic research—how things work• Applied research—making useful thingsSubmicroscopic world• Made of atoms• Link to make moleculesPhases of Matter• Three normal states at Earth’s surface– Solid– Liquid–Gas• How the molecules hold together• What is it like?• What phase?• Color• Reflectance• Odor• Density• Texture …Properties Properties• Physical changes– Usually dependent on conditions– New substance NOT created• Chemical changes– A reaction occurs– Transforms in to something different that has new propertiesWater—phase change Methane—chemical changeGuidelines to determine which has occurred• Return to original conditions– Do you get the original substance back?– Warm it up– Cool it down– Goes from ice to water– Goes from water to ice• Physical change2Guidelines to determine which• Return to original conditions– Do you get the original substance back?–Warm it up– Cool it down• Ammonium dichromate becomes ammonia, water vapor and chromium oxideGuidelines to determine which• Return to original conditions– Do you get the original substance back?–Warm it up– Cool it down• Potassium Chromate returns to yellow powderElements• Substances not bonded to other types of atoms• May be single atoms in elemental formula–Au Gold– Li Lithium• May have more than one atom to make molecules of that substance–O2oxygen–N2 nitrogenCompounds• More than one type of atom in the molecule• Has a Chemical Formula• Sodium Chloride NaCl• Ammonia NH3• Subscript tells how many of each• (Subscript 1 is omitted)Classes of matter Properties of elements• Very different from elements of their composition•Sodium– Shiny soft metal, – melts at 97oC– Reacts violently with water• Chlorine– Boils at -34oC– Toxic gasProperties of CompoundSodium Chloride• Clear, brittle solid at room temperature• Melts at 800oC• Not toxic—table salt• Not reactive with waterNaming compounds first word• Start with compound to the more left side of periodic tableNaming compounds second word• Add suffix –ide to the compound more to the right on the periodic table3Naming compounds NaCl• Sodium ChlorideNaming compounds Li2O• Lithium OxideNaming compounds CaF2• Calcium FluorideNaming different compounds of same elements• When more than one compound is formed from differing ratios of the same atoms, a prefix is added to distinguish them– Carbon Dioxide– Carbon MonoxideNaming Common CompoundsSome have traditional names• Water• Ammonia• Methane • Propane•etc.Naming
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