# Organic Chemistry: Bonding, Functional Groups, Acidity & Isomerism > 32 Organic Chemistry I review cards on hybridization, delocalization, functional-group structure, IUPAC nomenclature, acid–base and nucleophilicity trends, isomerism, and reactive intermediates. Assumes general chemistry. - **Canonical URL:** https://flashcards.world/flashcards/sets/848281ae-b338-46d5-a7c7-78b89fea94f1/ - **Markdown URL:** https://flashcards.world/flashcards/sets/848281ae-b338-46d5-a7c7-78b89fea94f1.md - **Level:** basic - **Languages:** en → en - **Total Cards:** 32 ## Flashcards (32 Cards) | # | Front (Term / Prompt) | Back (Definition / Answer) | Example | Multiple-Choice Options | | :--- | :--- | :--- | :--- | :--- | | 1 | In the usual hybrid-orbital model, what geometries and ideal angles correspond to sp³, sp² and sp carbon? | sp³: tetrahedral, about 109.5°; sp²: trigonal planar, about 120°; sp: linear, 180°. Assign hybridization from the local bonding and electron arrangement, not just the presence of a single bond. | | | | 2 | Do dispersion forces, dipole–dipole interactions and hydrogen bonds have a universal strength ranking? | No. Dispersion occurs in all molecules; permanent dipole interactions require polar molecules; hydrogen bonding requires suitable donors and acceptors. Polarizability, molecular size and geometry matter. Hydrogen bonding often raises boiling points among otherwise comparable compounds, but the categories alone do not determine the order. | | | | 3 | What is an acid anhydride, and why is it usually more reactive than an ester toward acyl substitution? | Its structure is R–C(=O)–O–C(=O)–R′: two acyl groups linked by oxygen. A carboxylate leaving group is less basic and generally leaves more readily than an alkoxide, helping make anhydrides more reactive under comparable conditions. | | | | 4 | How do chlorine substituents affect the acidity of acetic acid? | Chlorine withdraws electron density inductively through σ bonds and stabilizes the carboxylate conjugate base. Adding chlorine atoms near the carboxyl group generally lowers pKa; the inductive effect weakens with increasing distance. | | | | 5 | How do σ and π bonds differ, and why is rotation about a double bond hindered? | A σ bond has electron density along the internuclear axis; a π bond results from sideways orbital overlap on either side of that axis. Twisting a double bond disrupts π overlap. Single σ bonds can also have rotational barriers or ring constraints. | | | | 6 | Why is a typical peptide amide unit nearly planar, with hindered C–N rotation? | The nitrogen lone pair participates in conjugation with the carbonyl group, giving the C–N bond partial double-bond character. Rotation disrupts that overlap and has an energy barrier. It is hindered, not impossible, and no universal percentage of double-bond character applies. | | | | 7 | Why do alcohols generally boil at higher temperatures than comparably sized ethers or alkanes? | Alcohol molecules can form intermolecular hydrogen bonds through their O–H groups. These attractions generally increase the energy needed for vaporization. Molecular shape and size also matter, so this is a comparison of similar compounds, not a universal ranking. | | | | 8 | How do simple thiols and their conjugate bases compare with analogous alcohols and alkoxides? | Simple thiols are generally more acidic than analogous alcohols. Their thiolate ions are often stronger nucleophiles than analogous alkoxides in protic solvents, reflecting sulfur's polarizability and different solvation. Nucleophilicity still depends on the substrate and solvent. | | | | 9 | Why are acyl chlorides usually more reactive toward nucleophilic acyl substitution than esters or amides? | Their carbonyl carbon is strongly electrophilic, and chloride is a weak base and a good leaving group. Oxygen or nitrogen substituents in esters or amides donate by resonance more effectively, reducing carbonyl electrophilicity; their unprotonated leaving groups are also more basic. | | | | 10 | Why is phenol more acidic than cyclohexanol? | Phenol's conjugate base, phenoxide, delocalizes negative charge through the oxygen and aromatic π system. Cyclohexoxide lacks that conjugation. This additional stabilization makes phenol more acidic under comparable conditions. | | | | 11 | Why are terminal alkynes more acidic than otherwise comparable alkene or alkane C–H bonds? | The acetylide conjugate base places its lone pair in an sp orbital with 50% s character, compared with about 33% for sp² and 25% for sp³. Greater s character stabilizes negative charge closer to the nucleus in this comparison. | | | | 12 | What is a useful selected IUPAC seniority order for common functional-group classes, and why are alkenes, alkynes, ethers and halo groups treated separately? | Carboxylic acid > ester > acyl halide > amide > nitrile > aldehyde > ketone > alcohol > amine. This is a selected class order, not a complete naming algorithm. C=C and C≡C are indicated by ene/yne in the parent name; ether and halo groups commonly appear as alkoxy and halo prefixes. | | | | 13 | Using common introductory organic-chemistry table conventions, what approximate pKa benchmarks distinguish hydronium, acetic acid, phenol, water and ethanol? | Hydronium: about −1.7; acetic acid: 4.8; phenol: 10; water: 15.7; ethanol: 16. The water and hydronium figures use a common concentration-based teaching convention. Values and comparisons depend on solvent, temperature and standard-state conventions. | | | | 14 | What are the geometry and bonding of a nitrile group, R–C≡N? | In the usual hybrid-orbital model, the nitrile carbon is sp-hybridized and the R–C–N angle is approximately 180°. The C≡N bond contains one σ bond and two π bonds. | | | | 15 | Why is the carbonyl carbon electrophilic? | Oxygen draws electron density from the C=O bond, leaving carbon partially positive and oxygen partially negative. A nucleophile can donate an electron pair to the carbon. A charge-separated resonance contributor does not mean a free carbocation is present. | | | | 16 | Why are allylic and benzylic carbocations or radicals resonance-stabilized? | A vacant p orbital in a carbocation, or a singly occupied p orbital in a radical, can overlap with the adjacent π system. Positive charge or unpaired-electron density is then delocalized. This stabilizes them relative to comparable localized species, without making them necessarily long-lived. | | | | 17 | What four factors does the ARIO mnemonic highlight when comparing conjugate-base stability? | Atom: electronegativity and size of the charge-bearing atom; resonance: charge delocalization; induction: electron withdrawal through σ bonds; orbital: hybridization and s character. ARIO is a guide, not an inflexible ranking; solvent and the full structure also matter. | | | | 18 | How does nucleophilicity differ from Brønsted basicity? | Basicity describes a proton-transfer equilibrium; nucleophilicity describes the rate of attack on a specified electrophile under specified conditions. Solvent and steric hindrance can change nucleophilicity, so a strong base is not automatically a fast nucleophile in a given substitution reaction. | | | | 19 | Are cyclic hydrocarbons necessarily unsaturated? | No. Saturated hydrocarbons have only carbon–carbon single bonds; cycloalkanes are saturated. Carbon–carbon multiple bonds indicate unsaturation. The formula CₙH₂ₙ₊₂ applies to acyclic saturated hydrocarbons; a ring reduces the hydrogen count without creating a multiple bond. | | | | 20 | What are constitutional isomers? | Compounds with the same molecular formula but different atom connectivity. They can differ in carbon skeleton, functional group or its position. Their properties may differ; having different values for every physical property is not part of the definition. | | | | 21 | What acidity trends occur among simple second-row hydrides and among hydrogen halides? | The usual orders are CH₄ < NH₃ < H₂O < HF and HF < HCl < HBr < HI. Across the row, electronegativity matters; down the halogens, weaker H–X bonds favor acidity. Water levels HCl, HBr and HI to hydronium, masking their differences in ordinary dilute aqueous solutions. | | | | 22 | How is the degree of unsaturation calculated from a usual neutral organic molecular formula? | For conventional closed-shell valences, DBE = (2C + 2 + N − H − X)/2, where X counts halogens. Oxygen and divalent sulfur do not change the result. Each ring or double bond contributes one; each triple bond contributes two. Do not apply it blindly to ions or unusual valences. | | | | 23 | Why can a molecule with polar bonds have no net dipole moment? | Bond dipoles have directions as well as magnitudes, so molecular geometry can make them cancel. For example, the two C=O bond dipoles cancel in linear CO₂, whereas the O–H dipoles do not cancel in bent H₂O. | | | | 24 | Why is the usual stability order for simple unconjugated alkyl carbocations tertiary > secondary > primary > methyl? | Alkyl groups stabilize the electron-deficient center through hyperconjugation and electron donation. Adjacent σ bonds can overlap with its vacant p orbital. Resonance and other substituent effects can alter this simple ordering, so it is not a universal rule for all carbocations. | | | | 25 | What rough textbook pKa benchmarks apply to a simple ketone's α-C–H, a terminal alkyne, a neutral amine's N–H and an unactivated alkane C–H? | Approximately 20, 25, 35–40 and 50–60, respectively. These are rough teaching benchmarks, not a single-solvent data set. Neutral-amine N–H acidity must not be confused with the acidity of its protonated ammonium conjugate acid. | | | | 26 | What is a carboxylic ester, and what happens in Fischer esterification? | An ester contains the linkage –C(=O)–O–C–. Fischer esterification is the acid-catalyzed equilibrium between a carboxylic acid plus an alcohol and an ester plus water; it does not inherently go to completion. | | | | 27 | How do Lewis acids and Lewis bases differ? | A Lewis acid accepts an electron pair; a Lewis base donates one to form a bond. For example, BF₃ can accept a lone pair from NH₃. These definitions concern electron pairs, rather than requiring proton transfer. | | | | 28 | Why are simple carboxylic acids usually more acidic than simple alcohols? | Deprotonation gives a carboxylate ion whose negative charge is delocalized over two oxygen atoms. An alkoxide lacks this comparable resonance stabilization. Stabilizing the conjugate base generally favors acid dissociation under comparable conditions. | | | | 29 | Why are dry diethyl ether and THF commonly used with Grignard reagents? | They lack O–H groups that would protonate the reagent, and their oxygen lone pairs coordinate to magnesium. Water or alcohols instead consume the reagent by proton transfer. The reagent is an organomagnesium species, not a freely dissolved carbanion. | | | | 30 | How are primary, secondary and tertiary amines classified? | By the number of carbon groups attached directly to nitrogen: one in RNH₂, two in R₂NH and three in R₃N. This differs from classifying an alcohol or alkyl halide by the substitution of a carbon atom. | | | | 31 | How are primary, secondary and tertiary alkyl halides classified? | Count the carbon atoms directly bonded to the carbon bearing the halogen: one gives primary, two secondary and three tertiary. A methyl halide has no such carbon neighbors and is a separate case. | | | | 32 | What distinguishes an aldehyde from a ketone? | An aldehyde carbonyl carbon is bonded to at least one hydrogen: R–CHO, where R may also be H. A ketone carbonyl carbon is bonded to two carbon groups: R–C(=O)–R′. | | | --- Study this deck interactively with FSRS-6 spaced repetition, audio review, and multiple-choice mode at [Flashcards World](https://flashcards.world/flashcards/sets/848281ae-b338-46d5-a7c7-78b89fea94f1/).