CHEM 103 1st Edition Lecture 4Outline of Last Lecture I. TemperatureII. Scientific Notationa. Multiplying Scientific Notationb. Dividing Scientific Notation III. Significant Figuresa. Rules of Sig figsOutline of Current Lecture I. Significant Figuresa. Multiplying and Dividingb. Adding and Subtractingc. Conversiond. Percentage CalculationsII. DensityIII. Atoms and Moleculesa. Symbols and Formulasb. CompoundsCurrent LectureSignificant FiguresMultiplying and Dividing- Answer must contain the same number of significant figures as the quantity with the fewest number of significant figures used in the calculation- Ex: Multiplication: 4.325 (four sig figs) x 4.5 (two sig figs) = 19.4624 = 19 (two) Dividing: 4.325 (four) / 4.5 (two) = 0.9614 = 0.96 (two)These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.Adding and Subtracting- Answer must contain the same number of places to the right of the decimal as the quantity in the calculation with the fewest number of places to the right of the decimal. - Ex: Addition: 5.325 (three prd) + 5.5 (one prd) = 10.825 = 10.8 (one prd) Subtraction: 5.325 (three prd) - 5.5 (one prd) = -0.175 = -0.2 (one prd)In a problem with both multiplying/dividing and addition/subtraction, reduce the significant figures in the order you do the problems.Note: When in scientific notation, you MUST pay attention to sig figsConverting- Conversion Factors are fractions derived from fixed relationships- Ex: 1000 mL = 1 L- Conversion factors have no accuracy errors, so their significant figures are not counted. - Ex: A man runs a 100 meter dash in 13.5 seconds. Convert his sped to miles per hour. (Convert 100 m/13.5 sec to mph) 100 m is a fixed number, it will never change if the man runs another 100 meter dash.13.5 sec can change, and so this number can have errors and its 3 sig figs are counted.Our conversion factors are: 100 cm = 1 m, 1 in = 2.54 cm, 1 ft = 12 in, 1 mile = 5280 ft, 60sec = 1 min, 60 min = 1 hr100 m x 100 cm x 1 in x 1 ft x 1 mile x 60 sec x 60 min = 16.56989 mph = 16.6 mph13.5 sec 1 m 2.54 cm 12in 5280 ft 1 min 1 hrThe answer has 3 sig figs because 13.5 seconds is our only “imperfect” numberPercentage Calculations- To calculate percentage you place the # that is the part over the # that is the total and multiply it by 100 (part/total x 100 = percentage)- The 100 does not count in the significant figures, but otherwise treat the calculation with the same sig fig rules- Percent Accuracy: how accurate a product in an experiment is- Ex: % accuracy = actual/theory x 100- Percent Error: How far the product is from the theoretical answer - % Accuracy + % Error = % 100DensityThe ratio of the mass of a sample of matter divided by the volume of the same sampleDensity = mass/volumeDensity can also be found by its displacement for solids. If something is placed in 20 mL of water, and the measurement is now 25 mL, then its density is 5 mLWith liquids, the mass must be found by difference. The mass of the container must be found first, then the mass of the liquid and the container.- Liquid in container – container = liquidAtoms and MoleculesWhen chemically combined, elements can change drasticallySymbols and Formulas- Unique symbol for each element- Formulas represent compounds- All elements on the periodic table containo Mass of atomo Element nameo Symbolo Atomic number/ amount of neutronsElements we are expected to know the symbol and name of: Hydrogen – Krypton, Gold, Silver, Mercury, Lead, Copper, Iron, Sodium, Tin, Potassium, Uranium, ThoriumElements are found on the Periodic Table of ElementsCompounds- Compounds are expressed in formulas- Compound formulas consist of the symbols of each element in the compound- If there is more than one element in the compound, a subscript number following the element lists how many there are- Ex: CO (carbon monoxide), H2O (water), NH3 (ammonia), H2O2 (hydrogen peroxide)8OOxygen16.00Atomic number/ amount of neutronsSymbolNameMass of