Trap 1: Carbanion vs. Carbocation Stability Confusion
Error: Students apply the carbocation stability order (3° > 2° > 1°) to carbanions. Correct: Carbanion stability is the EXACT REVERSE: CH3- > 1° > 2° > 3°. Alkyl groups (+I effect) destabilize carbanions. Why: Alkyl groups push electrons — helpful for + charge (reduces it), harmful for - charge (increases it).
Trap 2: -OH is +I (Incorrect)
Error: Students classify -OH as a +I group because "O donates electrons." Correct: -OH is -I (O is electronegative, pulls electrons through sigma bonds) AND +M (O lone pair donates into pi systems). In sigma framework: -OH withdraws (-I). In pi/aromatic systems: -OH donates (+M). Key rule: O and N are ALWAYS -I but can be +M if lone pair is available for pi donation.
Trap 3: sp2 for CO2
Error: Students assume CO2 is sp2 because "it has double bonds like alkenes." Correct: CO2 carbon is sp hybridized (linear, 180°). Two double bonds = two sets of sigma bonds using sp orbitals, leaving two p orbitals for two pi bonds. Analogous to alkynes.
Trap 4: CH2=CH2 Showing Geometrical Isomerism
Error: Students assume any alkene shows E/Z isomerism. Correct: Both doubly-bonded carbons must each carry TWO DIFFERENT groups. CH2=CH2 has two identical H on each carbon — no E/Z isomerism. Same for CH2=CCl2 (two Cl on one carbon).
Trap 5: Meso Compound is Optically Active
Error: "Two chiral centers → optical isomers → optically active." Correct: A meso compound has chiral centers but an internal symmetry plane. The optical rotations of the two halves cancel. meso-Tartaric acid is optically INACTIVE despite two chiral centers.
Trap 6: Hyperconjugation Uses C-C Bonds
Error: Students count C-C bonds when calculating hyperconjugative structures. Correct: Hyperconjugation involves ONLY C-H sigma bonds alpha to the carbocation or pi bond. C-C sigma bonds are NOT involved in hyperconjugation (they contribute to inductive effect only).
Trap 7: Free Radical Stability = Carbanion Stability
Error: Students think free radicals follow the carbanion stability order (CH3• most stable). Correct: Free radical stability MIRRORS carbocation stability: 3° > 2° > 1° > CH3•. Both carbocations and free radicals are stabilized by alkyl groups (+I and hyperconjugation).
Trap 8: -Cl is Purely -I in All Contexts
Error: Students only remember the -I character of halogens. Correct: In aromatic rings, -Cl is ALSO +M (lone pair donates into ring). This makes -Cl an ortho/para director in EAS. The +M character in benzene competes with -I. For purely aliphatic context, -I only.
Trap 9: More Alkyl Substituents on Alkene = Less Stable Alkene
Error: Students think more substituents create steric strain and make alkenes less stable. Correct: More alkyl substituents on a double bond = more alpha-H = more hyperconjugation = MORE stable alkene. The Zaitsev product (more substituted) is the more stable elimination product.
Trap 10: IUPAC Numbering for Lowest Locant of First Branch (Not Principal Group)
Error: Students number to give the first branch the lowest locant, ignoring the principal functional group. Correct: The principal functional group ALWAYS gets the lowest possible locant, regardless of branches. For CH3CH(OH)CH(CH3)CH3: -OH gets C-2 (not C-3), making the name 3-methylbutan-2-ol, not 2-methylbutan-3-ol.