Chem 109 Midterm 2 Study Guide
Chem 109 Midterm 2 Study Guide Chem 109
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This 14 page Study Guide was uploaded by y-chen9 on Saturday October 17, 2015. The Study Guide belongs to Chem 109 at University of Wisconsin - Madison taught by Ive Hermans in Fall 2015. Since its upload, it has received 74 views. For similar materials see Advanced General Chemistry in Chemistry at University of Wisconsin - Madison.
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Date Created: 10/17/15
Chemistry 109 Midterm II Review By Yang Chen Professor Ive Hermans TA Hangjian Zhao Textbook Chemistry The Molecular Sciencequot Moore amp Stanitski 5e Structure of Crystalline Solids The structure of crystalline solids is made of a crystal lattice An orderly repeating arrangement of points in 3D space A unit cell is the smallest part of the lattice that when repeated only maintains the structure of the whole solid A cubic unit is one form of a unit cell It describes the unit cell in a cubic fashion In a cubic cell there are 3 common types 11 1 l 1 l w bltl quotle l k l i i l J z s I l l l l T l l V Kquot 7 if k r f gt7 g r gt r r m is 4 K L IN I m L t L f w c Facecentered cubic a Simple cubic b Bodycentered cubic In a primitive cubic unit cell there is a total of 1 atom In a primitive bodycentered cubic cell there are 2 atoms In a facecentered cubic cell there are 4 atoms The facecentered unit cell is the repeating unit of the cubic closepacked The most ef cient arrangement of spheres is found in the face centered cubic Each facecentered cubic has 12 neighbors CHAPTER 29 Organic Molecular Compounds Main Idea Organic means a compound has carbon All living things have carbon This includes the 3 main macromolecules for life proteins fats and carbohydrates The bonding properties of carbon allow it to form a huge variety of different molecules Hydrocarbon A compound containing carbon and hydrogen There are three kinds of hydrocarbons alkanes alkenes and alkynes ALKANES ALKENES ALKYNES All bonds are single 1 double bonds 1 triple bonds Saturated Unsaturated Unsaturated Longest bond length and shortest E bc electrons are further away from atom In between in both bond length and E compared to alkanes and alkynes No free rotation Shortest bond length and greatest E No free rotation No cistrans Yes free rotation Yes cistrans isomerism No cistrans isomerism isomerism CnH2n2 CnH2n CnH2n2 Simplest Simplest Simplest methane CH4 ethylene Acetylene C2H4 C2H2 Nonpolar Nonpolar Nonpolar lnsoluble in water lnsoluble but more soluble than alkanes lnsoluble but more soluble than alkanes and alkenes Low bp amp mp Low reactivity Moderate bp amp mp Moderate reactivity Highest bp amp mp Highest reactivity Reactions of alkanes httpswwwboundlesscomchemistrytextbooksboundless chemistrytextbookorganicchemistry23allphatichydrocarbons 163reactionsof alkanes6273623 lsomers Two or more compounds that have the same molecular formula but different placement of atoms Isomers Constituti nal Stereoisomers H I I Configurational Conf nrmati nal I I Ha g Genmetrin Uptical l I I Enanti mers CI Cl ll ll H II CHECHEJ IHH lijxm ma CH2 Hal ConstitutionalStructural Compounds with same formula but different order of bonded atoms Completely different properties Stereoisomers Molecules with same formula and sequence of bonded atoms but differ in the 3D orientations of their atoms 0 Conformational Differ by rotation about single bondssigma bonds A low energy process 0 Con gurational Does not differ by rotationnot conformers Conformation must involve the breaking and remaking of covalent bonds 0 Geometric Compounds with different arrangement of atoms around a double bond Some different properties 0 Cis same and trans different geometric isomerism 0 Optical Different arrangement of 4 different groups around a central carbon atom Mostly same properties 0 Enantiomers Nonsuperimposable mirror images 0 Disastereomers Superimposable mirror images can be chiral CHAPTER 6 67 Covalent BondingBond Properties H H H H H H39 Structural H quotf f f f H H H H H H H H H H H E K HR in L 3 it E H H E H Geometric Enantiomers Main Idea Bond length bond energy polarity and electronegativity are all different bond properties that impact the structure and function of covalently bonded molecules Bond length The distance between the nuclei of 2 bonded atoms This length is dependent on the lengths of the sizes of the individual molecules themselves Atomic radii increases as you go down groups and decreases as you go across a periods Bond length is measured in picometers pm Bond enthalpy Energy change when atoms are broken or remade in the gas phase at constant pressure 0 Bond breaking is an endothermic process 0 Bond making is an exothermic Polarity Results from the unequal sharing of electrons in a covalent bond Polar VS Nlonpolar Electronegativity The ability of an atom to draw bonding electrons to itself Electronegativity increases as you go across a period and decreases as you go down a group Fluorine is the most electronegative element 0 Connection between polarity and electronegativity The greater the difference in electronegativity between two atoms the greater the polarity will be between them CHAPTER 6 81 1 Covalent BondingFormal Charge LeWis Structures amp Resonance Exceptions to the Octet Rule Aromatic Compounds 0 Formal Charge The charge a bonded atom would have if its electrons were all shared equally among the atoms 0 FC of valence e of lone pairs of bondsH Smaller FC results in a more stable molecule and is therefore more favorable Negative FCs should reside on the more electronegative atoms Positive FCs should reside on less electronegative atoms Like charges should not be on adjacent atoms Resonance Structures Different Lewis structures that can be drawn for the same molecule Jill Itoquot O Octet Rule Exceptions o 1 Fewer than 8 Valence Electrons Makes the molecule very reactive 0 Ex BF3 o 2 Odd of Valence Electrons Involves free radicals Makes the molecule very unstable and reactive Will want to pair up with other free radicals 0 EX NO N03 0 3 More than 8 Valence Electrons Most common almost never in rst and second period Generally involves a central atom of C N O or F 0 Ex SF4 PF5 Benzene C6H6 The simplest of aromatic compounds It is often used as an industrial chemical It is a planar molecule so constitutional isomers are possible Q P V Elements Aromatic Compounds Hydrocarbon with benzene or benzene like ring All atoms in aromatic compounds participate in a network of pi bonds This makes them unusually stable Aromatic compounds have an aroma and are often used in cheap perfumes CHAPTER 716 Molecular Mode5 VESPR Hybridization Polarity Nonco valent Interactions anol Forces 0 We can predict the 3D structure of molecules based on 2D Lewis Structures 0 For drawing Names at types at chemical hendls used tn drew BID meleeuleir structures D rlenrtsitlehs ell ehemleeil hehdls lndlleeitedl by these styles d3 shed be rid hermet bend hend lies in the plane cut the paper er screen when stewed electrenicelly 0 Draw Lewis structure 0 Determine of structural e pairs around central atom 0 Determine e pair geometry from step 2 o Ignore lone pairs and describe molecular geometry Memorize or look at table 0 Dictate bond angle from molecular geometry Lone pairs have even greater repulsion Lone pairs will make bond angle smaller Electronregion Geometry Determined by of regions of bend exte hd s heckwe rds ewey t rem the triets39e r set etliecth ely quotinterquot the he per or screen wedged bend a o How to gure out moleculare geometry hend pretrudes ieheerds tewerds the viewer sci etliecth ely eut cl the he per er screen electron density around central atom Structural electron pairs 0 A lone pair a single double and triple bond are all ONE REGION 0 Molecular Geometry shape The arrangement of atoms in space that describes its physical shape 0 Lone pairs not included in this Structur e pair of of Molecular Bond al e geometry bonded lone geometry Angle pairs atoms pairs 5 2 Linear 2 0 Linear 180 3 Trigonal 3 O TT Planar 120 Triangular 2 1 Bent planar 4 Tetrahedr 4 O Tetrahedral 1095 al 3 1 TT Pyramidal 2 2 Bent Trigonal 5 O TT 90 Triangular 4 l Bipyramidal 120 Bipyrami 3 2 Seesaw 180 d 2 3 TShaped Linear Octahedr 6 O Octahedral 90 al 5 1 Sq Pyramidal 180 4 2 Sq Planar In the triangular bipyramidal structure there are equatorial equator and axial positions northsouth 0 Lone pairs occupy equatorial positions rather than axial positions In an octahedral structure all the bonds are equivalent So it makes no difference which apex the lone pair occupies o The angles do not become smaller if there is a lone pair VSEPR model can also predict 3D geometry of molecules with more than one central atom 0 Every carbon atom in an alkane has four bonds and is therefore a tetrahedral environment All 1095 degrees This makes the tetrahedron shape very important It is the basis of many biomolecules Chiral Molecules Molecules that have one or more stereocenters A stereocenter is a chiral atom in a molecule Being chiral means that it has 4 functional groups attached to the atom all of which are different An object that cannot be superimposed on its mirror image is called chiral o Objects that can be superimposed are all achiral o A chiral molecule and its nonsuperimposable mirror images are called enantiomers Hybridization When 2 atomic orbitals come together to make 2 hybrid orbitals that are identical in size shape and energy The of hybrid orbitals formed of orbitals combined 0 sp hybrid orbitals ls 1p l 2sp orbitals o spquot2 hybrid orbitals ls 2p l 3spquot3 orbitals o spquot3 hybrid orbitals ls 3p l 4spquot3 orbtias Sigma 0 Bonds Head to head orbital overlap single bonds Pi bonds are the strongest covalent bonds 0 MBo nds Sideways overlap of parallel p atomic orbitals that are unhybridized i Fi F39 orbital F39 orbital F39i Band 0 0 S Orbital S Orbital Sigma Orbital Polar Molecule Permanent dipole Electron density concentration is uneven in the molecule 0 Polar molecules have dipoledipole forces Nonpolar Molecule No overall separation of electric charge Dipole Moment resultant u The product of the magnitude of the partial charges 6 and 6 x the distance of separation between 6 and 6 0 Nonpolar molecules have dipole moment have a dipole moment of O 0 Polar molecules have positive dipole moments Greater dipole moment more polar A molecule can have polar bonds but still be nonpolar This happens when the bonds are arranged in a way that they cancel themselves out Noncovalent Bonding lonic or metallic bonding Intermolecular Forces Noncovalent interactions between 2 molecules They are all weaker than covalent bonds 0 London Forces All molecules have London forces temporary attractions between induced dipoles o DipoleDipole Forces Permanent attraction between dipoles of polar molecules 0 Hydrogen Bonding Weak lone pair bonds on N O F Strongest of the three bonds Alcohols and Their Oxidation Products All alcohols have an OH functional group directly bonded to a carbon atom 0 They therefore have hydrogen bonding and are often slightly 0 General formula CnH2n1OH Alcohols can be primary secondary or tertiary based on the position of the OH on the chain Identify the carbon in question and place your pencil on that carbon atom Then look at many lines emanate from the carbon atom that attach to another carbon This means the line does not lead to a hydrogen oxygen or halogen 0 Primary OH attached to 01 carbon with 1 alkylR group 0 Secondary 2 alkylR groups 0 Tertiary 3 alkylR groups f39 on O 0 Primary alcohols can be oxidized to produce aldehydes and then further oxidized to carboxylic acids 0 Aldehyde Alcohol dehydratedquot Alcohols are used as fuel preservatives and solvents CHAPTER 101 7 Fuels Organic Chemicals and Polymers Petroleum Organic compound of mix of alkanes cycloalkanes alkenes and aromatic hydrocarbons formed from plantanimal remains thousands of years ago Petroleum Mix of hundreds of hydrocarbons with boiling points in a certain range 0 Fossil Fuels Hydrocarbons that occur naturally in petroleum o Combustion CH4 202 l CO2 2H2 exothermic 0 Liquid fuel in cars Octane Number Measure of how well a gas burns in an engine 0 Can be increased by catalytic cracking Catalytic Cracking Breaks long straight hydrocarbon chains into branchedchain hydrocarbons and aromatic compound with high temperature high pressure and a catalyst Derivatives of Hydrocarbons Functional groups Alcohols and Their Oxidation Products 0 All alcohols have an OH functional group directly bonded to a carbon atom This ends a carbon chain 0 They therefore have hydrogen bonding and are often slightly 0 General formula CnH2n1OH Alcohols can be primary secondary or tertiary based on the position of the OH on the chain 0 Primary OH attached to 01 carbon with 1 alkylR group 0 Secondary 2 alkylR groups 0 Tertiary 3 alkylR groups 0 Primary alcohols can be oxidized to produce aldehydes and then further oxidized to carboxylic acids 0 Aldehyde Alcohol dehydratedquot Substance with CHO functional group 0 Carboxylic Acid Functional groups can be inside functional groups A carboxylic acid is the combination of a hydroxyl group and a carbonyl group They are ketones bonded to an OH group instead of an R group They all react with bases to form salts They are the acid part of amino acids which make up proteins Carboxylic acids react with alcohols in the presence of strong acids to produce esters Substance with a COOH functional group Alcohols are used as fuel preservatives and solvents Ketones Aldehydes bonded to R groups on both sides instead of a hydrogen on one side EstersEthers Alcohols with oxygen in the middle of a carbon chain 0 Only an ester if it s bonded to a carbonyl Esters are not very reactive and can easily be hydrolyzed Amine Terminal NH2 group 0 Polyamide Polymer with many amide linkages 0 Crash Course Derivatives of Hydrocarbons by Hank Green httbsWWIvy0utubec0mwatchvhXceEtBHA FLll E anI lg mum a The illflair Players Hg H iHEiizquot lE iH3 HgtltH I H alkana llk e aliltyne benzene ring iph ny F H i 3 L15th amine lmha E39 IEIquot alkyl halide thinl 39 2 39 a g 39 D quota D 39 s a 399 ILLH lateEH iiiHth aldehyrd Hailan eater certainty amide 0 acid Synthetic Organic Polymers Monomer monomer monomer l polymer l macromolecule Polymers can be synthetic 0 Food packaging clothes computers cars and many other things are made of synthetic polymers 0 There are 2 kinds of synthetic polymers 0 1 Thermoplastics Softens and ows when heated When it is cooled it hardens again 0 2 Thermosetting plastics First ows like a thermoplastic however when further heated it forms a rigid structure that can t be remelted Addition Polymer Made by adding monomer units directly together no other products are formed Involve one or more CC bonds Condensation Polymer Produced when monomer units combine to form the polymer and also release a small molecule usually water Organic Reactions 0 Addition Polymerization Monomer units are added together to each otherhookedup together 0 1 Initiation organic peroxides free radicals or each with an unpaired electron very reactive o 2 Propagation chain grows l huge polymer cc l cc o 3 Chain termination stops when the supply of monomers ends or when of free radicals is depleted Degree of polymerization of monomers in chain Biopolymers Polysaccha rides and Proteins Carbohydrates Mosnozsacchanides Oligosaccharides 39 Pclysaccharides glucoselructose sucrose lactose V siarohglycogen galactose maltose ral flnose cellulose bers Glycosidic Linkage A C O C that joins monosaccharaides together Two common polysaccharides are starch and glycogen They are both storage compounds that provide glucose for instant energy Starch is in plants while glycogen is in animals Cellulose is the most abundant organic compound on earth It is found in all plants However humans cannot digest it Amino acids are the building blocks of proteins They contain a carboxylic acid group and an amine group 0 Amino acids are linked together by peptide linkagesbonds to form polypeptides Primary structure amino acid sequence beta sheet Secondary structure regular substructures hemoglobin Tertiary structure threedimensional structure Quaternary structure complex of protein molecules Classifying Amino Acids If an amino acid is polarhydrophilic it can be acidic basic or neutral 0 You can tell if it is polar or not by comparing electronegativities of elements within the side chain S C and H are all relatively equal in electronegativity N is relatively equal with O N and O are more electronegative than S C H If the R groupside chain has an COOH it is acidic if it contains N it is basic If it has both neither or an amine group it is neutral 0 If an amino acid is nonpolarhydrophobic it is neutral mganic Nomenclature Background httpwwwchemuiuceduGenChemReferencesnomenclatureruesht Pre x substituent First Name carbon chain number Last Name type of chain Suf x highest priority functional group Steps to name organic compounds 1 Find the main chain 2 Locate the substituent groups on the main chain o 3 Locate the carbon atoms of the main chain so the sum of the substituent groups has the lowest sum 4 Name each substiuent group Indicate multiple groups by attaching pre xes to the group name 5 Indicate the location of each group by identifying the number of the Catom it is attached to When 2 or more substituents are present list the groups in alphabetical order ignoring any pre xes CHAPTER 1112 Rates of Reactions Measuring Rates 0 This that in uence the rate of a reaction 0 Nature of reactants some are more reactive than others 0 Concentrations of reactions and sometimes products 0 Temperature of reaction higher T generally means greater rate 0 Presence of catalyst For heterogeneous reactions greater surface area of a catalyst means greater reaction rate 0 De nition of reaction rate 0 General formula Rate change in concentrationchange in time However we must take in stoichiometry take coef cients Reactants have a quotminus signquot 0 Rate 1coeef change in concchange in time o Instantaneous Rate Rate 1coeff dcdt Find this study guide at httpsstudysoupcomuniversityof wisconsinmadisonchem 109bundlesept21october 2notetsid51690
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