OCR GCSE Chemistry A key terms

A solid’s surface area divided by its volume; it expresses how much surface is available for each unit of solid.

Everything outside the reacting substances that can exchange energy with them, such as the surrounding solution, container and air.

Using resources in a way that considers present benefits and the resources available for the future.

An organic compound produced deliberately through chemical reactions; it may be identical to a compound that also occurs naturally.

The part of the physical world chosen for study, including all the substances whose mass is being considered.

A straight line drawn to touch a curve at a chosen point and follow the curve's direction there.

To set a balance reading to zero, usually with an empty container on it, so that the next reading gives only the mass of the material added.

A thin, often discoloured surface layer formed when a metal reacts with its surroundings.

The difference between a measured final and initial temperature, usually recorded in °C.

Resistance to being pulled apart or stretched under a force.

A chemical added to a sample to produce an observable result that helps identify a substance.

A three-dimensional arrangement in which four bonds point towards the corners of a tetrahedron.

The greatest mass of a product predicted from the balanced equation, assuming the reaction proceeds completely and no product is lost.

The maximum amount of product predicted from the balanced chemical equation, assuming complete reaction and no losses.

A representation that shows or models length, width and depth, allowing the spatial arrangement of atoms to be examined.

The solution delivered from the burette during a titration.

An accurate method in which the measured volume of one solution needed to react completely with a measured volume of another solution is determined.

The volume delivered from a burette during a titration, calculated from the final reading minus the initial reading.

Thin layer chromatography, in which the supporting surface is coated with a thin layer of material such as silica or aluminium oxide.

Zeros written after the final non-zero digit; in a decimal value, they can show the precision with which the value is reported.

A metal in the central block of the Periodic Table, between Groups 2 and 3 in the usual school layout.

A regular change or pattern in data, such as an increase followed by a levelling off.

A flat representation with length and width but no physical depth, such as a diagram on paper.

An uncertainty is a limitation on how precisely a measurement or conclusion is known.

An indicator containing a mixture of dyes that produces a range of colours at different pH values.

A solution containing one or more species whose identities are to be determined.

The number of bonds that an atom can form; carbon has a valency of four in the structures considered here.