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Date Created: 09/18/14
CHM 1 14 91814 848 AM Chapter 1 In The Beginning BIG BANG Hit just the right spot in order to allow everything to happen During Big Bang there was a lot of Hydrogen H 0 There is also Deuterium and Tritium radioactive These are isotopes atoms with the same number of protons but a different number of neutrons o After 20 minutes the temp of the universe has cooled significantly o The first two elements have formed Hydrogen 75 of the universe and Helium with 25 Matter Anything that has mass and takes up space o Different Types Atoms of an Element Molecules of an Element Molecules of a compound Mixture of elements and a compound Atoms the building blocks of matter An element is made of the same kind of atom Elements can exist as single atoms as diatomic molecules or polyatomic molecules Some elements can exist in different forms or allotropes Compound is made of two or more different kinds of elements States of Matter Solid Liquid Gas Atoms Nucleus o Protons positively charged particle which defines an atom s identity 0 Neutrons particle with no charge but they have mass Weighs slightly more than a proton Don39t live long as neutrons Electrons o Negatively charged particles with 1100th the mass of a proton People are dumbasses and used nuclear bombs bunch of radioactive material dumped around 1940s The Elements Earth Wind Fire Water Elements are defined by the number of protons they have 82 Elements have been found on Earth 0 Gold Silver Lead Hydrogen Carbon 32 Elements have been created by scientists o Technetium Americium Seaborgium Very unstable Elements on the periodic table are on thing that every scientist will acknowledge regardless of language Periodic Table Systematic catalog of the elements Elements are arranged in order of atomic number Rows called periods Columns called groups Elements in the same group have similar chemical properties reaction types Periodicity when on looks at the chemical properties of elements one notices a repeating pattern of reactivities Groups 0 1A Alkali Metals o 2A Alkaline Earth Metals 0 6A Chalcogens 0 7A Halogens Don39t include H in this group 0 8A Nobles gases or rare gases Nonmetals are on the right side of periodic table with the exception of H Metalloids border the stair step line with the exception of Al Po and At Metals are on the left side of the chart 0 Base Quantity Name of Unit Symbol Length Meter m Mass Kilogram kg Time Second s Electrical Current Ampere Temperature Kelvin K Amount of Substnce Mole mol Luminous Intensity Candela cd While most scientists agree to the above convention there are other units or measurement that scientists use International System of Units SI For many people use miles instead of kilometers We use conversion factors to change one type of measurement into another Conversion factors have an infinite number of significant figures Symbols of Elements Elements are symbolized by one or two letters The Element Symbol o We use abbreviations to represent the elements as a form of short hand notation o Some elements like Hydrogen which has a symbol H should make sense as the symbol and name both begin with H o Iron Fe comes from the Greek word Ferrum which was a sword made from iron The mass of an atom in atomic mass units amu is the total number of protons and neutrons in the atom 0 Isotopes Atoms of the same elements with different masses 2 Isotopes have different number of neutrons Atomic Mass o Atomic and molecular masses can be measure with great accuracy using a mass spectrometer Average Mass 0 We use a weighted average for calculations involving mass Average mass is calculated from the stable isotopes of an element weighted by their relative abundances The Structure of the Atom JJ Thomson 0 Credited with the discovery of the electron in 1897 0 Measured the chargemass ratio of the electron to be 17610 8 coulombgram 0 Milikan OilDrop Experiment 0 Once the chargemass ratio of the electron was known determination of either the charge or the mass of an electron would yield the other Radioactivity o Spontaneous emission of radiation by an atom o It was first observed by Henri Becquerel 0 Marie and Pierre curie discovered them 0 Three types of radiation were discovered by Ernest Rutherford alpha positive charge Particles Beta negative charge Particles Gama no charge Rays 0 First atom mode presented by Thomson it was a plum pudding 0 It featured a positive sphere of matter with negative electrons imbedded in it o Rutherford challenged the first model idea 0 Shot alpha particles at a thin sheet of foil and observed the pattern of scatter of particles It was expected to go straight through however the particles were deflected from the nucleus Model changed form a plum pudding to a smaller space where most of the mass of the atom is located nucleus The nuclear atom 0 Since some particles were deflected at large angles Thomson39s model could not be correct 0 Rutherford postulated a very small dense nucleus with the electrons around the outside of the atom 0 Most of the volume of the atom is empty space Other Subatomic Particles o Protons were discovered by Rutherford in 1919 o Neutrons were discovered by James Chadwick in 1932 Protons and electrons are the only particles that have a charge Protons and neutrons have essentially the same mass The mass of an electron is so small we ignore it Proton 1 10073 amu Neutron 10087 0 Electron 1 5486e 4 amu Atomic theory of Matter The Daton s Postulates 0 Each element is composed of extremely small particles called atom o All atoms of a given element are identical to one another in mass and other properties but the atoms of one element are different from the atoms in another 0 Not changed into atoms of a diff element by chemical reactions atoms are neither crated nor destroyed the same way 0 Compounds are formed when atoms of more than one element combine a given compound always has the same relative number and kind of atoms Law of Conservation of Mass The total mass of substances present at the end of a chemical process is the same as the mass of substances present before the process took place Chemical Formulas The subscript to the right of the symbol of an element tells the O OOOO number of atoms of that element in one molecule of the compound Molecular compounds are the composed of molecules and almost always contain only nonmetals Diatomic Molecules Seven elements occur naturally as molecules containing 2 atoms 0 OOOOO 0 Types of Formulas Empirical Formulas o Lowest whole number ratio of atoms of each element in a compound For ionic compounds Molecular formulas o Exact of atoms of each element in a compound For molecular compound Structural formulas o Show the order in which atoms are bonded Perspective drawings o Show the 3D array of atoms in a compound Ions When atoms lose or gain electrons they become ions 2 types of ions o Cations Positive amp formed by elements on the left side of the p chart 1A 2A o Anions Negative amp formed by elements on the right side of the p chart Ionic Bonds o Ionic compounds such as NaC are generally formed between metals and nonmetals Writing Formulas Because compounds are electrically neutral one can determine the formula of a compound this way 0 The charge on the cation becomes the subscript on the anion o The charge on the anion becomes the subscripts on the cation 0 If theses subscripts are not in the lowest whoe number ratio dive them by the greatest common factor Inorganic Nomenclature Rite the name of the cation If the anion is an element change its ending to ide if the anion is a polyatomic ion simply write the name of the polyatomic ion If the cation can have more than one possible charge write the charge as a Roman numeral in parentheses Nomenclature of Binary Compounds The less electronegative atom is usually listed first A prefix is used to denote the number of atoms of each element in the compound mono is not used on the first The ending on the more electronegative element is changed to ide 0 CO2 carbon dioxide If the prefix ends with a or o and the name of the element begins with a with a vowel the two successive vowels are often elided into one Nomenclature of Organic Compounds Organic chemistry is the study of carbon Organic chemistry has its own system of nomenclature CHM 1 14 91814 848 AM Chapter 3 Law of Conservation of Mass During a chemical reaction atoms simply rearrange by breaking and creating bonds Matter is neither crated nor destroyed it is always present Total mass of reaction is constant 0 ie Start with 10 g end with 10 g Therefore a convention of tracking atoms though a chemical reaction is needed Number of molecules is the preferred method for tracking matter in a reaction because the same element can have different masses This the concept of the mole was invented The Mole Defined as the number of molecules present in 12 g of 12C Much like one dozen is 23 one mole is 602x1023 Molar Mass 0 The mass of 1 mol of a substance i1 gmol The molar mass of an element of an element is the ass number for the element that we find on the periodic table The formula weight in amu s will be the same number as the molar mass in gmol Formula Weight FW The sum of the atomic weights for the atoms in chemical formula So the formula weight of calcium chloride CaC2 would be 0 Ca 14008 amu o C 235453 amu 0 11099 amu Formula weights are generally reported for ionic compounds 10 g CaC2 1mo CaC2 6O2x1023 mol CaC2 110 g CaC2 1 mol CaC2 Molecular Weight MW Sum of the atomic weights of the atoms in a molecule For the molecule ethane C2He the molecular weight would be o C 212011 amu o H 6100794 amu 0 30070 amu Using Moles Grams gt use molar mass lt gt Moles lt gt avogadro s number lt gt formula units Mole Relationships One mole of atoms ions or melecules contains avogafros humber of those particles One mole of molecules of formula units contains avogadros number times the number of atoms or ions of each element in the compoiund Percent Composition One can find the percentage of the mass of a compound that ocmes from each of the elements in the compound by using this equation 0 o Element number of atomsatomic weightFW of the compound 100 So the percentage of C2Hs is 0 Finding Empirical Formulas Mass o elements gt assume 100 g sample gt grams of each element gt use molar mass gt Moles of each element gt calculate mole ratio gt empirical formula Calculating EF s o In Notebook 9214 Combustion Analysis Compounds containing C H and O are routinely analyzed through combustion in a chamber like the one shown in the Presentation 0 C is determined from the mass of CO2 produced 0 H is determined from the mass of H20 produced 0 O is determined by difference after the C and H have been determined Stoichiometric Calculations The coefficients in the balanced equation give the ratio of moles of reactants and products Once determined cant change if you determine it39s H20 then it stays as H20 Starting with the mass of Substance A you can use the ratio of coefficients of A and B to calculate the mass of Substance B formed if it39s a product or used if it39s a reactant Chemical Equations Concise representations of chemical reactions Anatomy of Chemical Equation o Products appear on the right side of the equation o Reactants appear on the left side of the equation o States of the reactants and products are written in parentheses to the right of each compound Solid Gas Liquid o Coefficients are inserted to balance the equation Subscripts and Coefficients give different information o Subscripts tell the number of atoms of each element in a molecule o Coefficients tell the number of molecules Balancing Chemical Equations 1 Write the correct formuas for the reactants on the left side and the correct formuas for the products on the right side of the equation 2 Change the numbers in front of the formulas to make the number of atoms of each element the same on both sides of the equation Do not change the subscripts 3 Start by balancing those elements that appear in only one reactant and one product 4 Balance those elements that appear in two or more reactants or products 5 Check to make sure that you have the same number of each type of atom on both sides of the equation Combination Reactions Two or more substances react to form one product o Examples 2Mgs O2g 9 2MgOs I N2g 3H2g 9 2NH3g Decomposition Reactions One Substance breaks down into two or more substances o Examples CaCO3s 9 CaOs CO2g 2KCO3s 9 2KCs O2g Combustion Reactions Generally rapid reactions that produce a flame Often involve hydrocarbons reacting with oxygen in the air o Examples I CH4g 202g 9 CO2g 2H20g I C4H8g 502g 9 3CO2g 4H20g Double Displacement Reaction C1A1 C2A2 9 C2A1 C1A2 CHM 114 LEARN TITRATION 91814 848 AM Chapter 4 Acids There are only seven strong acids 0 HCI HBr HI HNO3 H2SO4 OOOO Arrhenius defined bases as substances that increase the concentration of OHquot when dissolved in water Br nsted and Lowry defined hem as proton acceptors The strong bases are the soluble metal salts of hydroxide ion 0 Alkali metals 0 Calcium 0 Strontium o Barium AcidBase Reactions In an acid base reaction the acide donates a proton H to the base Neutralization Reactions Generally when solutions of an acid and a base are combined the products are a salt and water 0 CH3COOHaq NaOHaq 9 CH3COONaaq H2OI When a strong acid reacts with a strong base the net ionic equation is notes When solutions of an acid and a base are combined the products are a salt and water Gas Forming Reactions Some metathesis reactions do not give product expected In this reaction the expected product H2CO3 decomposes to give a gaseous product C02 0 CaCO3s 2HCaq 9 CaC2aq CO2g H2OI When a carbonate or bicarbonate reacts with an acid the products are a salt carbon dioxide and water Similarly when a sulfite reacts with an acid the products are a salt sulfur dioxide and water OxidationReduction Reactions An oxidation occurs when a n atom or ion loses electrons A reduction occurs when an atom or ion gains electrons One cannot occur without the other Oxidation Numbers To determine if an oxidation reduction reaction has occurred we assign an oxidation number Elements in their elemental form have an oxidation number of 0 The oxidation number of a monatomic ion is the same as its charge Nonmetals tend to have negative oxidation numbers although some are positive in certain compounds or ions 0 Oxygen has an oxidation number of 2 except on the peroxide ion in which it has an oxidation number of 1 0 Hydrogen is 1 when bonded to a metal 1 when bonded to a nonmetal o Fluorine always has an oxidation number of 1 The sum of the oxidation numbers in a neutral compound is 0 The sum of the oxidation numbers in a polyatomic ion is the charge on the ion Displacement Reactions In displacement reactions ions oxidize an element The ions then are reduced Molarity Two solutions can contain the same compounds but be quite different because the proportions of those compounds are different Molarity is one way to measure the concentration of a solution Mixing a Solution To create a solution of a known molarity one weighs out a known mass and therefore number of moles of the solute Dilution One can also dilute a more concentrated solution by 0 Using a pipet to deliver a volume of the solution to a new volumetric flask and 0 Adding solvent to the line on the neck of the new flask Titration An analytical technique in which one can calculate the concentration of a solute in a solution Dilution Problem 9 M1V1 M2V2 Where 1 concentrated and 2 dilute Salt metal nonmetal combined CHEM 114 91814 848 AM Chapter 5
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