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
“One molecule is oxidised while another is reduced — a chemical see-saw.”
Aldehydes without α-hydrogens disproportionate into an alcohol and an acid.
Memory trick: No α-H → self redox.
“That lone pair is what makes amines grab H⁺ and smell fishy.”
Amines are basic because nitrogen's lone pair accepts a proton.
Memory trick: Lone pair → base.
“The bright azo dyes in clothes start life as diazonium salts.”
Aryl diazonium salts are versatile intermediates for making dyes and substituted benzenes.
Memory trick: Gateway to azo dyes.
“String amino acids in the right order and you get anything from muscle to enzyme.”
The 20 building blocks of proteins, each with an amino and a carboxyl group.
Memory trick: Protein's alphabet.
“The recipe for you is written in a four-letter nucleotide code.”
DNA and RNA are polymers of nucleotides that store and express genetic information.
Memory trick: Store genetic code.
“A balanced diet supplies the amino acids your body can't build.”
Essential amino acids must come from diet; the body makes the rest.
Memory trick: Essential = from food.
“Detergents were invented so cleaning wouldn't fail in mineral-rich water.”
Soaps are salts of fatty acids (fail in hard water); detergents work even in hard water.
Memory trick: Detergents beat hard water.
“Each soap molecule is a tiny tadpole that traps dirt in the middle.”
Soap molecules have a water-loving head and an oil-loving tail, lifting grease into water.
Memory trick: Head loves water, tail loves grease.
“That chalky tablet after a spicy meal is simply neutralising acid.”
Basic compounds that neutralise excess stomach acid.
Memory trick: Base neutralises acid.
“Penicillin, found by accident, launched the antibiotic age.”
Chemicals that kill or inhibit bacteria; ineffective against viruses.
Memory trick: Target bacteria, not viruses.
“A metal catalyst quietly feeds nearly half the planet.”
Iron catalyses the Haber process that fixes nitrogen into ammonia for fertiliser.
Memory trick: Catalysts make industry viable.
“Three lenses, widening from H⁺ to full electron-pair chemistry.”
Acids give H⁺ (Arrhenius/Bronsted) or accept electron pairs (Lewis); bases do the opposite.
Memory trick: Lewis is the broadest definition.
“A quick bookkeeping system for tracking electron transfer.”
Free elements are 0, oxygen is usually −2, hydrogen +1, and the sum equals the ion's charge.
Memory trick: Sum = overall charge.
“Real reactions rarely give 100% — side reactions and losses eat into the total.”
Actual yield divided by theoretical yield, times 100.
Memory trick: Real ÷ theoretical × 100.
“Safe drinking-water limits for metals are quoted in ppm.”
Parts per million expresses very dilute concentrations.
Memory trick: 1 ppm = 1 mg per litre.
“Whatever mass goes into a sealed reaction comes back out.”
Mass is neither created nor destroyed in a chemical reaction.
Memory trick: Reactant mass = product mass.
“Water is always 8:1 oxygen to hydrogen by mass, from any source.”
A pure compound always contains its elements in the same fixed mass ratio.
Memory trick: Fixed ratio, always.
“A dartboard can be precise but off-target — tight but inaccurate.”
Accuracy is closeness to the true value; precision is repeatability.
Memory trick: Close vs consistent.
“It's the recipe maths of chemistry — how much yields how much.”
Using balanced equations to relate amounts of reactants and products.
Memory trick: Balance first, then ratio.
“Plant roots drink water by osmosis, and it's why salted slugs shrivel.”
Solvent flows through a semipermeable membrane from dilute to concentrated.
Memory trick: Solvent moves to the saltier side.
“Reverse osmosis purifies seawater by overpowering this pressure.”
The pressure needed to stop osmosis; a colligative property.
π = CRT
Memory trick: Depends on particle count.
“One mole of NaCl gives two particles, doubling its colligative effect.”
Accounts for particles formed when a solute dissociates or associates.
Memory trick: Counts actual particles.
“Spread ions farther apart and each carries current more freely.”
Conductivity per mole of electrolyte; it rises on dilution.
Memory trick: Increases with dilution.
“Every electrode potential is measured against this agreed zero.”
The reference electrode assigned a potential of exactly zero volts.
Memory trick: Reference = 0 V.