27 of the Chemistry glossary’s terms, each with the part of the syllabus where you first meet it.
The charge carried by one mole of electrons, ; it is the Avogadro constant multiplied by the charge of one electron.
The liquid or solution that passes through the filter paper during filtration.
Separation of an insoluble solid from a liquid or solution by passing the mixture through filter paper, which holds back the solid particles.
The part of an IR spectrum below about , with a complex pattern of absorptions unique to each compound; it is used to identify a compound by matching with a reference spectrum.
The energy change when one mole of electrons is added to one mole of gaseous atoms to form one mole of gaseous 1− ions:
The minimum energy needed to remove one mole of electrons from one mole of gaseous atoms in their ground state,
Describes a reactant for which the rate is proportional to its concentration: doubling the concentration doubles the rate. Its concentration falls with a constant half-life.
A curved arrow with half an arrowhead, used in mechanisms to show the movement of one electron, as in homolytic fission.
A test in which a compound is heated in a non-luminous flame; the colour of the flame, produced by the emission spectrum of the metal, identifies metal ions such as lithium, sodium, potassium, calcium and copper.
Removing sulfur dioxide from the waste gases of power stations before release, usually by reaction with a slurry of calcium oxide or calcium carbonate:
The charge an atom in a Lewis formula would have if all bonding pairs were shared equally: (valence electrons minus lone-pair electrons minus half the bonding electrons).
The group of ions or atoms given by the formula of a substance that is not made of molecules, such as one and one
In a reversible reaction, the reaction from left to right as the equation is written, turning reactants into products.
A fuel formed over millions of years from the buried remains of plants and other organisms: coal, crude oil or natural gas. Fossil fuels are non-renewable.
Distillation through a packed fractionating column, in which vapour repeatedly condenses and re-evaporates, to separate miscible liquids with similar boiling points; the most volatile component distils first.
A positive ion formed when a molecular ion breaks up; it gives a peak at the of the molecular ion minus the mass of the neutral fragment lost.
The breaking of a molecular ion in a mass spectrometer into a positive fragment ion, which is detected, and a neutral species (often a radical), which is not.
A substitution reaction that proceeds by a radical chain mechanism (initiation, propagation, termination), such as the reaction of an alkane with chlorine or bromine in UV light.
The change of state from liquid to solid, which releases energy (exothermic).
The number of waves passing a fixed point per second, symbol , in or Hz; it is inversely proportional to wavelength, .
A substance that releases useful energy when it reacts, usually by burning in oxygen.
A voltaic cell in which a fuel, such as hydrogen or methanol, and an oxidant, usually oxygen, are supplied continuously to two electrodes, converting chemical energy directly into electrical energy.
A formula that shows every atom in a molecule and every bond between the atoms, usually drawn flat with bonds at 90°.
A molecular allotrope of carbon made of closed cages of carbon atoms, such as ; the molecules are held together only by London forces.
An atom or group of atoms in a molecule that gives the compound its characteristic chemical properties; organic compounds are classified by their functional groups.
Structural isomers with different functional groups, such as ethanol and methoxymethane (
The part of an IR spectrum above about , where absorptions can be assigned to particular bonds and functional groups using a table of characteristic wavenumbers.