Chemistry key terms

The carbon–carbon double bond, C=C, that gives alkenes their characteristic reactions.

A different structural form of the same element in the same physical state.

Different structural forms of the same element, produced when its atoms are bonded or arranged differently.

A mixture of two or more elements in which at least one element is a metal.

Steel containing deliberately added metals to alter its properties for a particular use.

A positively charged particle used to investigate atomic structure in the Geiger–Marsden scattering experiment.

An investigation in which positively charged alpha particles were directed at thin metal foil and their paths after passing through or being deflected were observed.

An ionic compound with the formula Al₂O₃, containing aluminium ions and oxide ions.

A small organic molecule that acts as a building block for proteins.

A functional group written as –NH₂ in an amino acid.

A compound of nitrogen and hydrogen with the formula NH₃, used to manufacture nitrogen-based fertilisers.

A dissolved ion with the formula $NH_4^+$; it is different from ammonia gas, $NH_3$.

The salt $\mathrm{NH_4NO_3}$, used as a nitrogen-containing fertiliser.

A compound containing the ammonium ion, NH₄⁺, together with a negative ion.

A soluble salt containing ammonium ions, NH₄⁺, and sulfate ions, SO₄²⁻.

A quantity such as gas volume or mass that indicates how much reactant has been used or product has formed.

The amount of substance calculated by dividing its mass in grams by its molar mass in grams per mole.

The quantity of a substance measured in moles, rather than its mass or volume.

A condition in which oxygen is absent.

The breakdown of organic matter by microorganisms without oxygen.

Respiration that releases energy from glucose without using oxygen.

The substance in a sample that is being investigated.

Describes a substance from which its water of crystallisation has been removed.

A compound containing no water within its crystal structure.

A substance that contains no water, especially no water of crystallisation.

A negatively charged ion formed when an atom gains one or more electrons.

The positive electrode in electrolysis, where negative ions lose electrons.

A result that does not fit the pattern of the other results and may have arisen from an experimental problem.

A difference from a stated reference value or reference-period average.

Anthropogenic means caused by human activity.