Chemistry key terms

The reaction in which reactants form products as the equation is written from left to right.

A carbon-containing fuel formed from the buried remains of ancient organisms over millions of years; coal, crude oil and natural gas are examples.

Coal, oil and natural gas formed from ancient organisms and used as energy resources; their combustion releases carbon dioxide.

A group of hydrocarbons from crude oil whose molecules have similar numbers of carbon atoms and similar boiling points.

A process that separates crude oil into groups of hydrocarbons by evaporating them and condensing them at different temperatures.

A tall industrial vessel that is hot at the bottom and progressively cooler towards the top, allowing different fractions to condense at different levels.

Particles that are able to move or be released from a product, making exposure more likely.

Oxygen molecules, O₂, that are not chemically combined with other elements in a compound.

The change of state from a liquid to a solid.

Water with a low concentration of dissolved substances, such as rainwater collected in the ground, lakes and rivers.

A substance burned to release energy for heating, transport or electricity generation.

A cell that produces a potential difference by reacting fuel and oxygen supplied from outside it.

The complete sequence involved in supplying and using a fuel, including its production, storage, transport and final reaction.

A molecule made only of carbon atoms joined into a hollow shape, usually based on hexagonal rings.

All stages associated with something, from obtaining materials and making it through its use to its final disposal.

A drawing of a molecule that shows every atom and every covalent bond, including bonds to hydrogen.

A formula showing every atom and every covalent bond in a molecule.

An atom or group of atoms responsible for the characteristic reactions of an organic compound.

An additional enquiry designed to test a new question, extend the evidence or examine whether a result applies under other conditions.

Coating iron or steel with zinc to protect it from rusting.

An unfilled position in an arrangement of known elements, suggesting that an element had not yet been discovered.

A state of matter in which particles are widely spaced and move rapidly in different directions.

A gas formed in a chemical reaction that can leave an open reaction vessel.

A chemical reaction in which the substances being compared are gases under the stated conditions.

Equipment that removes a pollutant from a gas stream by bringing the gas into contact with a reacting material.

A graduated device whose plunger moves as gas enters, allowing the gas volume to be read from its scale.

A procedure that identifies a gas by a characteristic observable result.

A mesh placed on a tripod to support a vessel above a Bunsen burner and spread the heat.

An algebraic formula that represents every member of a homologous series using a variable such as $n$ for the number of carbon atoms.

A continuous network of very many atoms joined by covalent bonds rather than separate small molecules.