Week 1: Chapter 2 Notes
Week 1: Chapter 2 Notes CHE 2A
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This 7 page Class Notes was uploaded by CarolineTylerSmith on Tuesday September 29, 2015. The Class Notes belongs to CHE 2A at University of California - Davis taught by Dr. Tomoyuki Hayashi in Fall 2015. Since its upload, it has received 300 views.
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Date Created: 09/29/15
CHE 2A Week 1 of Notes CH 2 Hi my name is Tyler Smith and I am in CHE 2A Section A with Dr Tomoyuki Hayashi I will be taking notes during his lectures I will be uploading each week s notes on Tues or Wed for Study Soup These notes will not include lab information only lecture and some discussion information Ch 2 Atoms and the Atomic Theory Early Laws Law of Conservation of Mass I 2H209 02 4H Mass of Reactants Mass Products 410121600 9 21600 4101 3604gmol9 3604gmol Mass of H20 Mass of decomposed 02 and H Law of Constant Composition a molecule made up of multiple elements is always made up of the elements in the same composition every time If the composition is different it is no longer that molecule I ater H20 is 1802gmol lt H 2101 202 vi 0 11600 1600 0 16001802888 composition of H20 H20 1802 gmol H 2021802 112 composition of H20 100 This law states that water in order to be H20 it must have a composition of 112 H and 888 0 every time History of Atomic Theory Dalton s Theory 1 Atoms 2 Atoms cannot be created or destroyed or divided Fault this can happen in nuclear reactions 3 An atom of an element is always the same in mass and properties if it is that element Oxygen is always 1600gmol always made up of 8 protons 8 neutrons and 8 electrons Fault isotopes 4 when elements combine into compounds molecules they combine in whole rations leo 304 gt Wholelt Thomson Cathode Ray Tube Experiment From httpisitelpsorgsp utnamLHSlBIBChe mistryUNITZAtomic ZOStructurecathod eresultshtm Condenser plates IL 43 LmET r by in 1 1 e were shot through tube with an electrical force 2 2 the e was de ected away from the negative bottom plate and Magnet I M a 1 e were shot through a magnetic field B fields velocity and Force act at right angles of each other upwards towards the pOSmVe With the relationship between B Plat field V and force a particle must go Thus w1th like charges repelling and up with the force Because the unllke charges attract1ng electrons 1t electron stream goes downward it was concluded that electrons were must be a negative Charge Thus negatively Charged electron is negatively charged Coulomb s force qE Lorenz Force qu 2 3 7 C Here with both a magnetic and electrical field the electrons are balanced Therefore where Coulomb s Force Lorenz Force you will find the mass charge ratio of an electron Conclusions 1 Electrons are negatively charges 2 Electron s mass charge ratio is 56857x10399g C 3 Plum Pudding model Fault This Atomic Model is wrong later disproved by Rutherford Millikan Oil Drop Experiment FromhttpchemwikiucdaviseduWi kitexts N ewYo rkUniversity CHE MUA cover 1273AAdvancedGeneralChemistry l I O3 3AAnalysiso fkeyexperim ents 39 revealingthestructureoftheatoms oil I spra y 39 microscope f i H Mid gt E Would get measurements uniform electric eld like 16X1019C 32X1019C 1 Spray charged oil droplets and let them fall in between 6394X10 19C and 8390X10 19C Chargene The common multiple n of those measurements is e 16X103919C the charge of an electron two electrical plates 2 Measure how many volts of electricity were needed to suspend those charged droplets in place 3 You will find that the each measured reading of electricity was a multiple of 16X103919C Conclusions 1 charge of an electron 16x103919C Rutherford Gold F011 Exp erlment FromhttpchemwikiucdaviseduWi kitextsNewYorkUniversity CH EMUA 12 73AAdvancedGeneralChemistry I O3 3AAnalysisofkeyexperim ents revealingthestructureoftheatoms Alpha Particles are He 2 which are large positive particles 1 Shoot He2 particles through a foil only a couple atoms thick Copyright 2009 Pearson Prentice Hall Inc Lead Detector A very small amount of He2 bounce back Most He2 go right through Since it is a positive mostly empty space particle being repelled and rebounded there must be a small center that it is positive Some are slightly de ected nucleus of an atom Again repelling must be a positive center Conclusions 1 there is a small positive mass called a nucleus 2 most of the atom structure is empty space 3 the charge in a neutral atom is balanced by the small negative electrons around the nucleus The Atom From httpwwwuniverse todayc0m5 6747at omstru cture 6 protons 6 neutrons Charge Mass Proton 19 16022X103919C 39 16726X103924g Neutronn0 0 16749X103924g Electrone39 16022X103919C 91094X103928g Q electron a proton K o neutron Same but Basically Carbon atom opposite same mass charge Atomic Z of protons Atomic Number the protons is What gives the atom its chemical properties and thus its identity as that element Atomic Mass A protons neutrons A I Find the protons neutrons and electrons Protons 16 32 Protons 8 Neutrons 321616 S Neutrons 1688 Electrons 16 16 Electrons 8210 Cl37 Protons 17 atomic Neutrons 17 it is a neutral atom Electrons 20 3717 atomic massAtomic Protons 20 atomic Neutrons 24 4420 Electrons 18 Total charge pe therefore eptotal charge so e20218 Isotopes Different of neutrons changes nothing but the mass no chemical properties change Average Atomic Mass because of isotopes occurring in small percentages in elements we must find the average atomic mass for the element To find Average Atomic Mass mass ofisotope 1X of abundance ofisotope1 mass of isotope 2X abundance ofisotope 2 I Find the average atomic mass of Mass of Isotope Abundance Oxygen 160 1599491463 99757 170 169991312 0038 180 179991603 0205 1599491463x99757169991312X 0038 179991603X0205 1595604865 00064596699 0036804865 159994066amu I Atomic Mass Unit amu or u it is used for finding the average atomic mass of elements I Potassium atomic mass39098 has two naturally occurring isotopes K39 and K41 What is the percent abundance of each isotopic mass 1 assign variables K39 389637 1X the whole 100 value K41 40 9618 X a value 3896371x409618 X 39098 409618X 389637X 39098389637 x00672 X100gt 672 abundance for K41 and 1006729328 abundance of K39 Mass Spectrograph a device used to find the masses of all the isotopes in an element Using a magnetic field I the lighter isotopes easier to push and be affected by the field are turned more and end up closer on the plate I the heavier isotopes being harder to push or be affected by the field travel the farthest along the plate 801 Abundance Ions 199 10 1 2 Boron Mass I Detector Force due to Lorenz forces is identical in the mass spectrograph but the acceleration of the different isotopes are different depending on mass so they end up at different points of the detector The Periodic Table Periodic Table of the Elements Atomic nunber Alkaline earth mails Metauoids Hement symbol Land39ianides mm nonmem 13 1s 16 17 Henwntnane 3A 5A 6A 7A Atomic weight Acumdes Halogens 5 39IIIIII39 1Tan th1nxnak IIIIIII Nobkrgases E3 Unknown properties 80mquot 3 v A quot 28 i 7 33 n 39 Hf Periods 74922 49 50 51 5 2 5 In Sn Sb Te um Tin Antimony Telluriun 11432 11871 12176 12760 81 82 85 84 s Tl Pb Bi Po Thauiun Lead Bismuth Poloniun 20438 2072 20898 209 110 111 113 114 115 116 117 118 7 D5 Rg Uut Fl Uup Lv Uus Uuo Unllmilm Herovium Ununpcmium Limmotiu39n Ununnptium Ununoctium 268 268 268 268 268 268 268 168 268 nides Lanthan Groups SOURCES National Institute of Standards and Yechnology International Union of Pure and Applied Chemistry KARL TATE LiveSciencecom etals conductors form cations lose electrons become positively charged malleable and ductile Nonmetals non conductors forms anions gains electrons becomes negatively charged not ductile or malleable Metalloids share qualities of non metals and metals at the same time Periodic Table of the Elements w J M PE 59 60 6 Pr Nd Pm Pruudmun Nadyhm F39cmu lm 5 1421509 mm mm Molar Mass Atoms being so small and numerous are impossible to count with numbers so we must use molar mass weight to find out how many atoms molecules are in a sample It is the weight of one mole of atoms gmol Different units from Atomic Mass amu or u but same value Mole is the amount of a substance it is a measurement like a quotdozen eggsquot or a pair of shoesquot you say I have a mole of Carbonquot I 1mol 6022x1023atomsmolecules Avogadro s Number I A sample of lead weights 1135 grams how many atoms are in the block 1135g X 1mol X 6022X1023 atoms 33X1022 atoms 20mg 1n7ol