OCR GCSE Chemistry A key terms

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.

A formula that represents every member of a homologous series using a variable such as $n$.

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

A regular, repeating three-dimensional arrangement containing very many oppositely charged ions.

A regular, repeating three-dimensional arrangement of particles extending throughout a solid.

A structure containing a very large, continuous arrangement of bonded atoms or ions rather than separate small molecules.

A reduction in the sunlight reaching Earth’s surface because particles in the atmosphere scatter or block it.

A long-term rise in the Earth's average surface temperature.

The steepness of a graph, calculated as the change in the vertical quantity divided by the change in the horizontal quantity.

The natural warming of the Earth’s surface and lower atmosphere because certain atmospheric gases absorb and re-emit outgoing infrared radiation.

A gas, such as carbon dioxide or methane, that absorbs infrared radiation emitted by the Earth and contributes to the greenhouse effect.

A vertical column of the Periodic Table whose elements have the same number of outer-shell electrons and often react in similar ways.

An industrial process that reacts nitrogen with hydrogen to manufacture ammonia.

A chemical equation showing the electrons gained or lost by a species in one part of a redox reaction.

A compound containing a halogen combined with another element; examples include sodium chloride and potassium bromide.

A negatively charged ion formed when a halogen atom gains one electron, such as chloride, bromide or iodide.

An element in Group 7 of the periodic table; halogens form diatomic molecules and can gain electrons to form halide ions.

A graph showing how the temperature of a substance changes as energy is transferred to it.

A protective surface placed beneath heating apparatus to shield the bench from heat.

The largest whole number that divides every number in a ratio exactly.

A group of compounds with the same functional group and similar chemical properties; successive members differ by CH₂.

A substance containing water as part of its crystal structure.

A compound containing carbon and hydrogen atoms only.

A positively charged ion, written as H⁺, whose concentration affects the pH of a solution.

The amount of hydrogen ions present per unit volume of solution.

A negatively charged ion made of hydrogen and oxygen, represented by OH⁻.

An unwanted substance mixed with the substance being tested.