From elements to real substances.
Water, salts, sugars and gases are built from elements, but their behaviour depends on bonding, geometry and structure. Search by a familiar name or formula, or enter through a chemical idea you want to understand.
Fifty compounds chosen to teach different chemical ideas.
The collection is still curated by chemistry rather than alphabetically. Search for a name or formula, or use the cards as conceptual entry points.
Water
Bent molecular geometry and intermolecular hydrogen bonding.
Carbon dioxide
Polar bonds can combine to a zero molecular dipole.
Ammonia
A lone pair shapes both geometry and proton-transfer chemistry.
Methane
The simplest alkane and a clean lesson in molecular symmetry.
Sodium chloride
Why an ionic crystal is not a collection of NaCl molecules.
Calcium carbonate
Ionic solid outside, resonance-delocalized carbonate inside.
Sodium bicarbonate
Baking-soda chemistry without confusing compound and mixture.
Sodium hydroxide
Na⁺ and OH⁻ in the solid and hydrated ions in water.
Hydrogen chloride
See how molecular HCl becomes hydrochloric acid when it dissolves in water.
Sulfuric acid
Two proton-transfer steps that are chemically unequal.
Hydrogen peroxide
The O–O bond changes everything compared with water.
Ethanol
A polar hydroxyl end attached to a small hydrocarbon chain.
Acetic acid
From –COOH to acetate, while keeping vinegar distinct.
Glucose
Cyclic forms, stereochemistry and reducing-sugar behaviour.
Fructose
Same formula as glucose, different connectivity and chemistry.
Sucrose
Glucose and fructose units joined through both anomeric centres.
Nitric acid
One acidic O–H group and nitrate chemistry.
Phosphoric acid
Three stepwise proton transfers.
Citric acid
Three carboxyl groups plus one alcohol group.
Urea
Resonance and hydrogen bonding kept conceptually separate.
Acetone
A compact introduction to carbonyl polarity.
Benzene
A delocalized six-carbon ring.
Silicon dioxide
Why quartz is not made of tiny O=Si=O molecules.
Carbon monoxide
Strong bonding and subtle polarity.
Sulfur dioxide
A clean contrast with linear CO₂.
Nitrogen dioxide
An odd-electron molecule that forms N₂O₄.
Methanol
The simplest alcohol and a clean comparison with ethanol.
Formaldehyde
Keep pure CH₂O distinct from formalin solutions.
Glycerol
Three hydroxyl groups on a flexible three-carbon chain.
Ethylene glycol
Two –OH groups connect methanol and glycerol conceptually.
Lactic acid
A stereogenic center without silently choosing one enantiomer.
Oxalic acid
Two carboxyl groups and two deprotonation steps.
Ethyl acetate
Connect ethanol and acetic acid through ester chemistry.
Phenol
Why ring–OH is chemically different from an ordinary alcohol.
Toluene
A benzene ring with one covalently attached methyl group.
Propane
Single bonds, saturation and combustion.
Ethene
Double bonding, planarity and restricted rotation.
Ethyne
Triple bonding and the 180° geometry of the simplest alkyne.
Sodium carbonate
Ionic outside, resonance-delocalized carbonate inside.
Calcium hydroxide
Strong-base chemistry without confusing strength and solubility.
Iron(III) oxide
A real solid-state oxide, not a five-atom molecule or a synonym for rust.
Aluminium oxide
Extended bonding, passivation and amphoteric behavior.
Magnesium oxide
A 1:1 formula unit in a rock-salt-type extended solid.
Potassium nitrate
K⁺ outside a trigonal-planar nitrate polyatomic ion.
Ammonium nitrate
Tetrahedral ammonium plus trigonal-planar nitrate.
Ammonium chloride
Link NH₄⁺ / NH₃ acid-base chemistry back to ammonia.
Sodium hypochlorite
Pure compound identity kept separate from bleach formulations.
Potassium permanganate
A tetrahedral high-oxidation-state polyatomic ion.
Copper(II) sulfate
Anhydrous CuSO₄ kept separate from CuSO₄·5H₂O.
Calcium sulfate
Anhydrite, gypsum and hemihydrate kept chemically distinct.