ChemistryChapter 13Central Science• Study of matter• Transformations if 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 …PropertiesProperties• 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 changeMethane—chemical changePhysical or Chemical• Choose which is whichGuidelines 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 changeGuidelines 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)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 1• Start with compound to the more left side of periodic tableNaming compounds 1• Add suffix –ide to the compound more to the right on the periodic tableNaming compounds 1• Sodium ChlorideNaming compounds 1• Lithium OxideNaming compounds 1• Calcium FluorideNaming compounds 2• 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 Compounds 3• Some have traditional names• These are common compounds•Ammonia• Methane, propane• Water•etc.Naming
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