Central Science Chemistry Study of matter Transformations it can make Basic research how things work Applied research making useful things Submicroscopic world Made of atoms Link to make molecules Chapter 14 Phases of Matter Three normal states at Earth s surface Solid Liquid Gas How the molecules hold together Water phase change Properties What is it like What phase Color Reflectance Odor Density Texture Methane chemical change Properties Physical changes Usually dependent on conditions New substance NOT created Chemical changes A reaction occurs Transforms in to something different that has new properties Guidelines 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 change 1 Guidelines 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 oxide Guidelines to determine which Elements Return to original conditions Do you get the original substance back Warm it up Cool it down Potassium Chromate returns to yellow powder 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 O2 oxygen N2 nitrogen Compounds Classes of matter Properties of elements Very different from elements of their composition Sodium 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 Shiny soft metal melts at 97o C Reacts violently with water Chlorine Boils at 34o C Toxic gas Properties of Compound Sodium Chloride Clear brittle solid at room temperature Melts at 800o C Not toxic table salt Not reactive with water Naming compounds first word Start with compound to the more left side of periodic table Naming compounds second word Add suffix ide to the compound more to the right on the periodic table 2 Naming compounds NaCl Sodium Chloride Naming 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 Monoxide Naming compounds Li2O Lithium Oxide Naming Common Compounds Naming compounds CaF2 Calcium Fluoride Naming compounds Some have traditional names Water Ammonia Methane Propane etc 3
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