Chem- C 101 1st EditionExam # 1 Study Guide Lectures: 1-3This exam is very conceptual. Study these terms and concepts, but also do extra problems for practiceand be able to apply them. Read the corresponding chapters in the text book. Do CALM work. Examcovers chapters 1-3 and potentially some of 4. Chapter 1:Chemistry: explanation of natural phenomena, from experience-central science-bridge between principles of physics and practice of biology-study of matter and changes it under goesTechnology: application of scientific knowledgeScience: explanation of structure of atomMatter: stuf-has mass and occupies space-some difficult to detect ex.) air1. Pure Substances- single matter is present2. Mixture- 2 or more pure substances, solution or solidEx.) NaCl= table salt + water + sugar Uncommon example is rocka. Homogeneous- same throughout= solutioni. Ex.) tsp sugar in cup waterii. Air= N2 and O2b. Heterogeneous- diferent= rock gardeni. May appear homogeneousii. Ex.) sugar mixed with saltElements: 118 total. 94 natural, 24 man made2 Types of Pure Substances:1. Elemental- atoms of one element a. Gold or oxygen2. Compounds- atoms of 2+ diferent elements a. Water or sugarTransformations in Matter:1. Physical Transformation of pure substance changes from state tostareand stays same pure substance-Physical properties of water-3 states of mater: solid, liquid, gas2. Chemical Transformation- way pure substance behaves when combined with other pure substancesEx.) Na(metal) + water= fireScientific Method:- Ask questions Background ResearchHypothesisExperiementAnalyze/ conclusion Hypothesis Hypothesis false Try Again/ Go back to Hypothesis True Report Results-Independent Variable: what you change-Dependent Variable: outcome-Law: generalization that summarizes the outcome of a series of experiements-Theory: attempt to explain why a law exists-Model: Physical picture of mathematical expression of theoryChapter 2:-Numerical quantities presented 2 ways1. Exact NumbersEx.) 7 days/week, money -count it, no uncertainties, measurement-Precision: closeness to one another in a series of measurements of same object- need several measurements to compare-Accuracy: How close to the true value, based on average measurement, only need one measurement tocompare2. Uncertainty and Significant Figures-measurements with a device-visual observation- to correct we can assume the measured value has range of uncertainty-we arrive at that range by assuming uncertainty is in tenth positionRounding Numbers: drop of non-significant digits in a calculation and adjusting the last digit reportedRules: Determine number of significant figures the final result should have and look at digit to be droppedA. If digit is >5 or 5 followed by non zero digit, add 1 to last digit to be retained and drop all digits furthest to the righta. Round 1.2151 to 3 sig. figures = 1.22B. If digit is < 5, drop it and all numbers furthest to righta. Round 1.2143 to 3 sig. figures= 1.21C. If digit is 5 or 5 followed by 0’s and if the last digit to be retained is even, drop the 5 and any0’s after it. If last digit is odd add 1 to it and drop 5 and any zeros after ita. 1.245=1.24 1.24500=1.24 1.23500=1.24Zeros and Significant Figures: -If given a measurement and not sure of the measuring device used, assume uncertainty is in the last written digit-All digits in 203.8 are significant-0.08 has 1 significant figure because zeros are place holders when they are leading Leading Zeros: All zeros that come before the first non zero digit, generally found in numbers with absolute value <1-703.2 has no leading zeros-0.00102 has 3 significant figuresRules for Zeros: -leading zeros in a decimal number less than 1 arent significant -zeros that follow a nonzero digit are significantTrailing Zero: zero to the right of non zero digit-leaving out a decimal point in a measurement is not allowedArithmetic with Significant DigitsTO ADD/SUBTRACT MEASURMENTS: -Perform the operation then round result to correspond with measurement having least number of decimal places-24.686+2.343+3.21=30.239=30.24TO MULTIPLY/DIVIDE MEASUREMENTS: -Note factor with least significant digits and round to those numbers of digits-3.22 cm x2.1 cm=6.762 cm squared=6.8 cm squaredChapter 3:Scientific Notation: convenient way of expressing numbers – A x 10^xA= number with decimal point X=exponent/power of 10 25000= 2.5 x 10^4 A=2.5 X=4X will always be whole number and tells you what todowith decimal point-Exponent is positive=move right2.5 x 10^4 = 25000-Exponent is negative= move left2.35 x 10^-3 = .00235-Exact numbers don’t efect number of significant figures you end up with-220 hours x 3 = 660 hours-exact number is 322.0 miles x 2.0 miles = 44. Miles = 4.4 x 10^1 miles squaredConvert 20.17 yards to mm in scientific notation:20.17 yds x 3ft x 12in x 254cm x 10mm = 18443.448=1.844 x 10^4 mm 1yd 1ft 1in 1cmIMPORTANT EQUATIONS: Fahrenheit Scale: Degrees F = 32+ 9/5 degrees CCelcius: Degrees C= 5/9(Degrees F-32)Density: D=Mass/VolumeEnergy: capacity to do work-unit of energy= calorie-1000 cal=1 Calorie –used by dietician-takes 1 calorie of heat to warm 1 gram of water from 25 degrees Celsius to 26 degrees Celsius-1 degree temperature increase is unnoticeable by your hand-1000 calorie= 1 Calorie would increase same gram of water by 1000 degrees Celsius assuming water remains liquid-unit of energy used by chemist/physicist-Joule-4.184 J/cal or cal/4.184 J-4.184 kJ/Cal or Cal/4.184 kJSpecific Heat: amount of heat energy (cal or J) needed to warm 1 gram of a substance by 1 degree CelsiusLaw of Chemical Combination: -law of conservation of mass-during chemical reaction, neither gained nor lost-mass of reactant= mass of productProportion vs. Percent:Proportion of element in compound is ratio of mass of element to total mass of compoundPercent is proportion x 100Ex.) N2O2 N= 2(14)=28gO= 1(16)=16gMolecular Weight= 44g%N= 28/44 x100 =63.64%O= 16/44 x 100= 36.36Subatomic Particles: -atoms are not indivisible-Made up of many subatomic particles1. Protons- positive. In nucleus2. Neutrons- no charge. In nucleus3. Electrons- negative. Outside nucleus-Small nucleus- radius is 1/10000 of atom-attraction of negative and positive charges holds electrons in atomAtoms: -electrically neutral (number of protons= number of electrons)-neutrons don’t efect charge-number of protons determine atoms identity-atomic number is