Week 2 notes
Popular in General Chemistry Lecture I
Popular in Chemistry
This 5 page Class Notes was uploaded by Maggie Cummings on Friday September 11, 2015. The Class Notes belongs to CHE106 at Syracuse University taught by Doyle in Summer 2015. Since its upload, it has received 55 views. For similar materials see General Chemistry Lecture I in Chemistry at Syracuse University.
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Date Created: 09/11/15
CHAPTER 1 NOTES o Most substances are compounds o Compound substance compounds composed of two or more elements chemically compound 0 Smallest unitmolecule o The law of definite proportions states that pure compound always contains constant proportions of the elements by mass Mixture a material that can be separated by physical means into two or more substances 0 Unlike a pure compound a mixture has uneven composition 0 Classified as o Heterogeneous physically distinct parts o Homogeneous uniform physical parts o Mathematical skills 0 Scientific notation o A x 10quotn o A number between 1 and 10 o N exponent positive or negative integer o 48543 4853x 10quot3 00568 568x10A2 o Basic Shift decimal point to the rightleft to produce A a number between 1 and 10 Count how many places you moved itgtngtexponent o If you moved leftgt npositive if moved rightgt nnegative o Rounding o Procedure for dropping non significant digits in a calculation and adjusting last reported digit o Rules o Look at the digit to be droppedgt if 5 or higher add 1 to the last digit to be retained and drop all others to the right o If it is less than 5 drop it and all digits to the right o Measurement and Significant Figures 0 Measurement comparison of a physical quantity to be measured with a unit of measurement o Has precision and accuracy 0 Precision refers to the closeness of a set of values obtained from identical measures of a quantity Accuracy refers to the closeness of a single measurement to its actual value To indicate a precision of a measurement we use sig figs Significant Figures digits in a measured number than include all certain digits and a final digit having some uncertainty 0 An exact number has no effects on significant figures because an exact number arises when you count items or define a unit 0 Significant Figures o All non zero digits are significant 12344sig figs o Zeroes between significant figures are significant 102345 sig figs o Zeroes preceding the first non zero digits are not significant 0004573 sig figs o Zeroes to the right of the decimal after a nonzero digit are significant 1230006 sig fgs o If not a decimal number then the zeroes at the end maymay not be significant o 900 Buuut 90004 sig figs 0 Applying math functions to significant Figures o When multiplying and dividing give as many sig figs as the least amount found in the measurement o 14012041367175 gt 01373 sig figs 0 Error Filename not specified When adding and subtracting give the same number of decimals as the least found in the measurement Number after decimal o 18422324186524gt1865 o When multiple functions are present o 32056104523 o Evaluate everything in the first o Do any multiplication and division o Do any additionsubtraction o 32056104523 o 32052654130233363 o 233363 x 10quot3 o 23 x 10quot3 gt 2 sig figs Units 0 Use SI system international system 0 7 base units Mass gram g or kilograms kg Length meter m Time seconds Temperature Kelvin K Amount of substance mole mol Electric current Ampure A Luminosity Condelo cd 0 SI is a metric ie Decimal system 0 Temperature o Kelvin K the true measure of temperature since it is the measure of the average kinetic energy of the particle in your sample 0 degrees27315 degrees celecius K degrees celcius 27315 Degrees celecius degees ferenheit3218 Water freezes at 27315 degrees K 0 degrees Celcius 32 degrees ferenheit o Water Boils at 37315 degrees K 100 degrees Celcius 212 degrees ferenheit o Derived Units 0 Speeddistance travelled in unit time o Slgt meterssecond Second SI unit of length o Meters SI unit of length 0 Volume lengthquot3gt cmquot3 o This formula is great for solids but not for liquids o Liquids liters or milliliters o Gasses o 1 cmquot3 1mL o 1mquot31deciliter o 1Liter decimetersquot3 o 1milliliter 1cmquot3 0 Density massvolume o Mass measured in grams or kilograms o Volume measured in milliliters mL for liquid cmquot3 for solids and Liters for gasses o Example lead sulfide mass1249g and a volume of 164mquot3 What39s the density o D124g164cmquot3 7509gcmquot3 Unit gramscmquot3 o Dimensional Analysis 0 Keep the units with the numbers as you go so you can make sure the right units come out at the end 0 Needs the concept of conversion factors o Examplegt express the speed of light 299792458 meterssecond in mileshour o msgtmph o 1609m1 mile 3600 seconds1 hour o 299792458ms x3600sec1hr x 1 mile1609 meters mileshour o Answer once everything is multiplied cancelled and divided 6707600055 o 67076005 x 10quot8 6708 x 10quot 8 report last answer with correct significant figures CHAPTER 2 o Atomic theory and structure 0 John Dalton credited with formulation of atomic theory of matter 0 His theory offers an explanation of the structure of matter 0 Dalton had four principles o All matter is composed of indivisible atoms o An element is a type of matter composed of only one type of atom Each atom of the element has the same properties o A compound is a type of matter composed of two or more elements chemically combined in fixed proportions o A chemical reaction consists of the rearrangements of the atoms in the reacting substances to give new chemical combinations Atoms are not created or destroyed or broken into smaller particles by any chemical reaction Atomic symbols o Hgt hydrogen etc Note that Dalton39s postulates were put forward in the late 18th and early 19th centuries Earnst Rutherford o Atoms were mostly empty space and contained subatomic particles o His experiment showed that the atom consists of two distinct areas o The nucleuspositively charged One or more electrons light weight and negatively charged Robert Milliken 1909 US physicist o Measured the charge of the electron JJ Thompson o Worked out ratio of electron mass to charge o Between Milliken and Thompson the mass of the atom was calculated o 9109 x10quot31 kg o 18000 smaller than the smallest atom H o Atoms made of smaller particles Rutherford proposed his quotnuclear modelquot and his famous quotGold Leafquot experiment gave it credibility o Found particles from spontaneous radioactive decay of gold foilgt most passed through the foil only1 in 8000 deflected o Reasongt aside from the core nucleus most of the atom is empty space
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