Fundamentals
The core facts every aspirant should own — each a titled nugget with a real-world story, the concept in plain words, and a memory trick. Works even when the internet doesn't.
300 fundamentals
“Every medicine, plastic and fuel is a story written in carbon.”
Electrophiles are electron-poor (seek electrons); nucleophiles are electron-rich (donate electrons).
Memory trick: nucleophile = nucleus-loving = electron donor; electrophile = electron-loving = acceptor.
“Every medicine, plastic and fuel is a story written in carbon.”
A frequent error is swapping the two definitions. In reality, electrophiles are electron-poor (seek electrons); nucleophiles are electron-rich (donate electrons).
Memory trick: nucleophile = nucleus-loving = electron donor; electrophile = electron-loving = acceptor.
“Every medicine, plastic and fuel is a story written in carbon.”
A frequent error is ranking a primary carbocation as more stable than a tertiary one. In reality, order 3° > 2° > 1°, because alkyl groups donate electrons and stabilise the positive charge.
Memory trick: more alkyl groups → more stable carbocation (hyperconjugation + inductive).
“Every medicine, plastic and fuel is a story written in carbon.”
The inductive effect works through sigma bonds and fades with distance; resonance works through pi systems and can act over long conjugation.
“Every medicine, plastic and fuel is a story written in carbon.”
SN1 goes through a carbocation in two steps (favoured by 3° substrates); SN2 is a one-step backside attack (favoured by 1° substrates).
“Every medicine, plastic and fuel is a story written in carbon.”
They don't flip back and forth — the molecule is one stable resonance hybrid.
“Petrol, cooking gas and candle wax are all hydrocarbons — just different chain lengths.”
Alkanes are saturated (only single bonds); alkenes and alkynes are unsaturated (double or triple bonds).
Memory trick: double/triple bonds are reactive sites — unsaturated hydrocarbons react more readily.
“Petrol, cooking gas and candle wax are all hydrocarbons — just different chain lengths.”
A frequent error is thinking unsaturated hydrocarbons are less reactive than alkanes. In reality, alkanes are saturated (only single bonds); alkenes and alkynes are unsaturated (double or triple bonds).
Memory trick: double/triple bonds are reactive sites — unsaturated hydrocarbons react more readily.
“Petrol, cooking gas and candle wax are all hydrocarbons — just different chain lengths.”
A frequent error is reversing it, except in the peroxide (anti-Markovnikov) effect. In reality, when HX adds to an alkene, H attaches to the carbon that already has more hydrogens.
Memory trick: 'the rich get richer' — the H-rich carbon gains the H.
“Petrol, cooking gas and candle wax are all hydrocarbons — just different chain lengths.”
Extra stability of planar, cyclic, fully-conjugated rings with (4n+2) pi electrons (benzene).
Memory trick: benzene prefers substitution because addition would destroy its aromatic stability.
“Petrol, cooking gas and candle wax are all hydrocarbons — just different chain lengths.”
A frequent error is expecting benzene to undergo addition like an alkene. In reality, extra stability of planar, cyclic, fully-conjugated rings with (4n+2) pi electrons (benzene).
Memory trick: benzene prefers substitution because addition would destroy its aromatic stability.
“Petrol, cooking gas and candle wax are all hydrocarbons — just different chain lengths.”
An alkane has only single C–C bonds (saturated, reacts by substitution); an alkene has a C=C double bond (unsaturated, reacts by addition).