ACS Organic Chemistry Semester 1 question and answers

  formal charge - Correct Answers: group # - lone pairs (NBE) - bonds (1/2 valence electrons) valence electrons - Correct Answers: electrons in the outer most shell Atom - Correct Answers: Smallest particle of an element protons+neutrons surrounded by electrons octet rule - Correct Answers: States that atoms lose, gain or share electrons in order to acquire a full set of eight valence electrons Pauli Exclusion Principle - Correct Answers: An atomic orbital may describe at most two electrons, each with opposite spin direction Aufbau Principle - Correct Answers: states that each electron occupies the lowest energy orbital available first Hund's Rule - Correct Answers: states that single electrons with the same spin must occupy each equal-energy orbital before additional electrons with opposite spins can occupy the same orbitals single bonds - Correct Answers: - Sigma bonds, contains two electrons. * Permit free rotation double bonds - Correct Answers: 1 sigma and 1 pi bond triple bonds - Correct Answers: 1 sigma and 2 pi bonds atomic number - Correct Answers: equal to the number of protons neutrons - Correct Answers: equal to the atomic mass - atomic number isotopes - Correct Answers: where the same element has the same number of protons (mass number) but different amount of neutrons, resulting in a different mass number (12C AND 13C) shells - Correct Answers: n=1 1 shell 2electrons 1s2 n=2 2 shell 8 electrons 2s2 2p6 n=3 3 shell 18 electrons 3s2 3d10 3p6 ionic bond - Correct Answers: Formed when one or more electrons are transferred from one atom to another (metal/nonmetal) covalent bond - Correct Answers: A chemical bond that involves sharing a pair of electrons between atoms in a molecule non polar covalent bond - Correct Answers: equal sharing of electrons polar covalent bond - Correct Answers: unequal sharing of electrons common bonding patterns: C - Correct Answers: 4 valence electrons 0 lone pairs 4 bonds common bonding patterns: N - Correct Answers: 5 valence electrons 1 lone pair 3 bonds common bonding patterns: O - Correct Answers: 6 valence electrons 2 lone pairs 2 bonds common bonding patterns: X halogens - Correct Answers: 7 valence electrons 3 lone pairs 1 bond common bonding patterns: H - Correct Answers: 2 valence electrons 0 lone pairs 1 bond Resonance - Correct Answers: - cannot break (or make) any single (sigma) bonds - the overall charge must stay the same - move pi electrons or lone pairs is allowed hybridization - Correct Answers: the mixing of several atomic orbitals to form the same total number of equivalent hybrid orbitals hybrid orbitals - Correct Answers: lone pairs + sigma bonds sp hybridization - Correct Answers: hybrid orbitals: 2 geometry: linear bond angle: 180 sp2 hybridization - Correct Answers: hybrid orbitals: 3 geometry: trigonal bond angle: 120 sp3 hybridization - Correct Answers: hybrid orbitals: 4 geometry: tetrahedral bond angle: 109.5 constitutional isomers/ structural isomers - Correct Answers: isomers whose atoms are connected differently; they differ in their bonding sequence cis isomer - Correct Answers: an isomer of an alkene in which the hydrogen atoms in the double bond are on the same side; the bulky groups are on the same side trans isomer - Correct Answers: an isomer of an alkene in which similar groups in the double bond are on opposite sides; bulky groups are on opposite sides cis-trans isomers - Correct Answers: One of several compounds that have the same molecular formula and covalent bonds between atoms but differ in the spatial arrangements of their atoms owing to the inflexibility of double bonds; formerly called a geometric isomer. example of cis/trans - Correct Answers: bond dipole moment - Correct Answers: separation of charge in a bond that depends on the difference in electronegativity and the bond distance represented by partial charges or a vector molecular dipole moment - Correct Answers: the vector sum of the individual dipole moments in a compound intermolecular forces - Correct Answers: forces of attraction between molecules; when 2 molecules approach, they either attract or repel each other dipole-dipole interactions - Correct Answers: attractive forces that act between polar molecules London dispersion forces - Correct Answers: The intermolecular attractions resulting from the constant motion of electrons and the creation of instantaneous dipoles; a temporary dipole moment in a molecule can induce a temporary dipole moment in another molecule Hydrogen bonding - Correct Answers: strong type of intermolecular dipole-dipole attraction. Occurs between hydrogen and F, O or N (O-H tends to be stronger than N-H) Arrhenius acid - Correct Answers: substance that dissociated in H2O to give H3O+ Arrhenius base - Correct Answers: substance that dissociates in water to produce OH (hydroxide) ions Bronstead-Lowry Acid - Correct Answers: proton (H+) donor Bronstead-Lowry Base - Correct Answers: accepts H+ ion pKa: the characteristic of a particular compound and it tells you how readily the compound will give up a proton (how easily it can be lost ) - Correct Answers: pKa=-logKa pKa values - Correct Answers: pKa1 very strong acid, very good donor of proton pKa 1-5 moderately strong acid pKa 5-15 weak acid pKa 15 extremely weak acid (basic) factors that effect acidity - Correct Answers: 1: electronegativity (more electronegative, more acidic) 2: size (increases with increasing size) 3: resonance (more resonance, more acidic) Lewis base - Correct Answers: electron pair donor nucleophile Lewis acid - Correct Answers: electron pair acceptor electrophile Alcohol - Correct Answers: Ether - Correct Answers: Aldehyde - Correct Answers: Ketone - Correct Answers: carboxylic acid - Correct Answers: Acid Chloride - Correct Answers: Ester - Correct Answers: Amide - Correct Answers: Amine - Correct Answers: Nitrile - Correct Answers: Thiol - Correct Answers: Thioether - Correct Answers: Disulfide - Correct Answers: Nomenclature of Alkanes - Correct Answers: 1. find the longest continuous chain of carbons 2. number starting with closest to the substituent 3. alphabetize, lowest possible numbers isopropyl - Correct Answers: isobutyl - Correct Answers: Eclipsed Ethane projection - Correct Answers: 0 degrees Staggered Ethane projection - Correct Answers: 60 degrees Skew Ethane projection - Correct Answers: not a multiple of 60, very off ethane projections - Correct Answers: high energy, low stability low energy, high stability Totally Eclipsed Butane Projection - Correct Answers: 0, 360 degrees-- totally blocking each other highest energy, low stability Gauche Butane Projection - Correct Answers: 60, 300 degrees-- energy minima Eclipsed Butane Projection - Correct Answers: 120, 240 degrees -- high energy but lower than totally eclipsed Anti Butane Projection - Correct Answers: 180 degrees-- lowest energy, high stability cyclohexane conformations - Correct Answers: chair - most table, minimizes three types of strain c1 - dashed - axial c2 - wedged - axial c3 - dashed - axial cyclohexane conformations chart - Correct Answers: TRANS: 1,2: A,A OR E,E 1,3: A,E OR E,A 1,4: A,A OR E,E CIS: 1,2: A,E OR E,A 1,3: A,A OR E,E 1,4: A,E OR E,A stability of carbocations - Correct Answers: 3 2 1 methyl stability of free radicals - Correct Answers: 3 2 1 methyl stability of carbanions - Correct Answers: methyl1*2*3* Free Radical Halogenation of Alkanes - Correct Answers: 1) initiation 2) propagation 3) termination Stereoisomers - Correct Answers: molecules that have the same structural formulas and bonding patterns but different arrangements of atoms in space Diastereomers - Correct Answers: stereoisomers that are not mirror images cis/trans isomers Enantiomers - Correct Answers: non superimposable chiral, mirror images that always exists in pairs chiral carbon - Correct Answers: A carbon atom attached to four different atoms or groups of atoms. (R)- rectus - Correct Answers: clockwise (S)- sinister - Correct Answers: counter clockwise Cahn-Ingold-Prelog priority rules - Correct Answers: priority is given by looking at the atoms connected to the chiral carbon or double-bonded carbons - whichever has the highest atomic number gets highers priority - if there is a tie, one moves outward from the chiral carbon or double bond until the tie is broken when R-- S, vice versa - Correct Answers: when the lowest priority is not behind the plane, the configuration switches Fischer projection - Correct Answers: A method of drawing organic molecules in which horizontal lines are coming out of the page (wedges) and vertical lines are going into the page (dashes) 2n rule - Correct Answers: A molecule with n chiral centers might have as many as 2n stereoisomers # of possible stereoisomers, where n= chiral carbons any compound that can rotate plane polarized light is - Correct Answers: optically active polarimeter - Correct Answers: an instrument that measures the rotation of plane-polarized light by an optically active compound specific rotation - Correct Answers: a= degree observed c= concentration of sample l= path length optical purity - Correct Answers: enantiomeric excess - Correct Answers: alkyl halide nomenclature - Correct Answers: named as alkanes with a halide position and group name ex: 2-Iodopropane SN2 reactions - Correct Answers: Bimolecular nucleophilic substitution reactions occur through a concerted mechanism where the nucleophile attacks as the leaving group starts to leave SN2 characteristics - Correct Answers: rate= k[nucleophile][substrate] - back side attack - strong nucleophile - good leaving group - concerted rxn; 1 step - inversion configuration - transition state - substrate reactivity (CH312) - solvent polar APROTIC SN1 reactions - Correct Answers: Unimolecular nucleophilic substitution reactions. Leaving group leaves, forming a carbocation that then reacts with a nucleophile SN1 characteristics - Correct Answers: rate= k[sub] - possible rearrangements (carbocation) - weak nucleophile - good leaving group - 2 steps & deprotonation if needed - racemic mixture - substrate reactivity (321) - solvent polar PROTIC (H2O, ROH) nucleophilicty - Correct Answers: decreases across periodic table increase down periodic table polar parotid solvents for SN2 - Correct Answers: acetonitrile CH3-C (triple bond) N acetone CH3C(double bond) O CH3 dimethylformamide E/Z nomenclature - Correct Answers: more than one double bond when cis/trans fails the higher the priority means higher the atomic number and this is what show was is labeled one of each side. E: entogegen - Correct Answers: opposite sides Z: zussamen - Correct Answers: same sides E2 reactions - Correct Answers: bimolecular rate=k[substrate][base] strong base 321 1 step process Zaitsev's Rule - Correct Answers: in elimination reactions, the most stable alkene is the most highly substituted alkene essentially: most highly substituted, least hydrogens Hoffman Product - Correct Answers: in elimination reactions, the least substituted double bond is the most stable (only happens when there is a bulky base) essentially: least substituted, most hydrogens bulky bases - Correct Answers: t-butoxide diisopropylamine triethylamine 2,6-dimethylpyridine E1 reactions - Correct Answers: unimolecular rate= k[sub] weak base 321 (same reactivity as E2) 2 step process rearrangements dehydrogenation of alkanes (-H2) - Correct Answers: REAGENT: heat & catalyst (some type of metal: Pt, Pd, Ni) a double bond will result Dehalogenation of vicinal dibromides (-Br2) - Correct Answers: REAGENTS: Na+I- OR Zn,CH3COOH results in a double bond in the place of the vicinal dibromides E1 dehydration of alcohols (-H2O) - Correct Answers: REAGENTS: H+, H2O alcohol-- alkene look for possible rearrangements to make the most stable double bond OH leaves Addition Hydrogenhalide (HX) to Alkene (hydrohalogenation) - Correct Answers: alkene-- alkyl halide REAGENTS: HX ex. HBr notes: markovnikov rearrangments Markovnikov's Rule - Correct Answers: The addition of a proton acid to the double bond of an alkene results in a product with the acid proton bonded to the carbon atom that already holds the greater number of hydrogen atoms extended rule: in an electrophilic addition to an alkene, electrophile adds in such a way as to generate the most stable intermediate free radical Alkene-- alkyl halide - Correct Answers: REAGENTS: HBr, ROOR note: ANTIMARKOVNIKOV aka H+ is added to the Carbon with the least H's Addition of water to alkene (hydration) - Correct Answers: alkene-- alcohol REAGENTS: H+, H2O note: markovnikov carbocation rearrangements (OH most stable) Oxymercuration-Demercuration - Correct Answers: alkene-- alcohol REAGENTS: 1) Hg(OAc)2,H2O 2) NaBH4 note: markovnikov antiaddition Alkoxymercuration-Demercuration - Correct Answers: alkene-- ether REAGENTS: 1) Hg(OAc)2, ROH 2) NaBH4 note: markovnikov anti addition (opp sides) Hydroboration - Correct Answers: alkene-- alcohol REAGENTS: 1)BH3:THF 2) H2O2, NaOH, H2O note: anti mark (H goes to C w least Hs, OH goes to most) syn addition (same sides)