chm115_lecture2

chm115_lecture2 - 2-1Chemistry 115Dr Raftery...

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Unformatted text preview: 2-1Chemistry 115Dr. Raftery [email protected]://www.itap.purdue.edu/tlt/blackboardLecture 2 OutlineChapter 1Chapter 2What is Chemistry?Atomic Theory TodayScientific MethodSymbolic Representation The Three Types of Matter Isotopes and Atomic Mass Units, Errors, Significant Figures Periodic TableDimensional AnalysisIons, Ionic CompoundsNaming Ionic CompoundsHW1:ReviewSee OWL for assignmentDue Wednesday, January 20IN RECITATIONRecitation (Jan 15):Review Chapters 1,22-2What is chemistry?Chemistry is the study of matterMatter can be classified in a number of ways—physical state - gas, liquid, solid(also plasma)—pure substances or mixtures—Chemical compositionPropertieswe can measure regarding a substance1) Physical - doesn't change chemical identityEx.: color, hardness, density, melting pointa physical change is a change of state: liquid -> gas2) Chemical - how a substance reactsflammabilityhydroscopic- a chemical change changes the chemical identityBurnH2+ O2H2O∆(not balanced)puremixture2-3Scientific MethodIncreasing CO2concentrationsTrapped CO2raises tempsFurther Experiments:Measure ave temps around globeGlobal WarmingScientific method leads to characteristics of good experiments:Change 1 variable at a time, Reproducible, (Quantitative)Test prediction with other weather phenomena.2-4Making MeasurementsChemistry is both a qualitative(what?) & quantitative(how much?) scienceUnits:We use the metric system of units to describe the quantitationPhysical QuantityName of UnitAbbreviationMassKilogramkgLengthMetermTimeSecondsaElectric currentAmpereATemperatureKelvinKLuminous intensityCandelacdAmount of substanceMolemolTABLE 1 SI Base UnitsaThe abbreviation sec is frequently used.2-5PrefixAbbreviationMeaningExampleMega-M1061 megameter (Mm) = 1 X 106MKilo-k1031 kilometer (km) = 1 X 103mDeci-d10-11 decimeter (dm) = 0.1 mCenti-c10-21 centimeter (cm) = 0.01 mMilli-m10-31 millimeter (mm) = 0.001 mMicro-μa10-61 micrometer (μm) = 1 x 10-6mNano-n10-91 nanometer (nm) = 1 x 10-9mPico-p10-121 picometer (pm) = 1 x 10-12mFemto-f10-151 femtometer (fm) = 1 x 10-15mTABLE 2 Selected Prefixes Used in the SI SystemaThis is the Greek letter mu (pronounced “mew”).2-6Experimental Errors- All measurements involve errors2-7What are their definitions?2-8Two terms describe errors:1) accuracy – how close to the "true" value limited by systematic errors2) Precision – reproducibilitylimited by random errorsErrors are indicated by a ± symbol, such as:Length = 10 ± 0.1 cm....
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chm115_lecture2 - 2-1Chemistry 115Dr Raftery...

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