Every chemistry term,
clearly explained.
960 curated entries across 16 branches — each with a definition, the key formula or equation, its unit and a worked example.
Physical Equilibrium
An equilibrium between two physical states or phases of the same substance.
Browse by branch
16 branches of chemistry, from atomic structure to biochemistry.
Acids, Bases & Salts
Acid · Acid Dissociation Constant · Acid Strength and Molecular Structure and more
60 termsAnalytical Chemistry & Spectroscopy
Analyte · Analytical Chemistry · Atomic Absorption Spectroscopy and more
60 termsAtomic Structure & Periodicity
Alkali Metals · Alkaline Earth Metals · Atomic Emission Spectrum and more
60 termsBiochemistry & Polymer Chemistry
Addition Polymerisation · Adenosine Triphosphate · Amino Acid and more
60 termsChemical Bonding & Molecular Structure
Antibonding Molecular Orbital · Back Bonding · Bent Geometry and more
60 termsChemical Equilibrium
Activity · Activity Coefficient · Approach to Equilibrium and more
60 termsChemical Kinetics & Catalysis
Activated Complex · Activation Energy · Active Site and more
60 termsElectrochemistry & Redox
Anode · Anodising · Calomel Electrode and more
60 termsFoundations of Chemistry
Accuracy · Allotropy · Anhydrous and more
60 termsInorganic & Coordination Chemistry
Alloy · Ambidentate Ligand · Bidentate Ligand and more
60 termsNuclear & Radiochemistry
Alpha Decay · Artificial Radioactivity · Background Radiation and more
60 termsOrganic Chemistry
Alcohol · Aldehyde · Aldol Condensation and more
60 termsSolutions & Colligative Properties
Abnormal Molar Mass · Aerosol · Aqueous Solution and more
60 termsStates of Matter & Gas Laws
Absolute Zero · Amorphous Solid · Anisotropy and more
60 termsStoichiometry & Chemical Reactions
Activity Series · Actual Yield · Addition Reaction and more
60 termsThermochemistry & Thermodynamics
Adiabatic Process · Bomb Calorimeter · Bond Dissociation Enthalpy and more
Equations worth knowing
One cornerstone formula from each corner of the dictionary.
Acid
A substance that donates protons, produces hydrogen ions in water, or accepts a pair of electrons.
Analytical Chemistry & SpectroscopyAtomic Absorption Spectroscopy
A technique that measures the concentration of a metal from the light its free gaseous atoms absorb.
Atomic Structure & PeriodicityAlkali Metals
The group 1 elements — lithium through francium — which have a single valence s electron.
Biochemistry & Polymer ChemistryAddition Polymerisation
Polymerisation in which unsaturated monomers add to one another with no loss of any atoms.
Chemical Bonding & Molecular StructureAntibonding Molecular Orbital
A molecular orbital higher in energy than its parent atomic orbitals, whose occupation destabilises the molecule.
Chemical EquilibriumActivity
The effective concentration of a species, corrected for non-ideal interactions with its surroundings.