Chemistry key terms

A repeated or recognisable relationship in data.

A scientist with suitable knowledge of the same field as the researcher whose work is being evaluated.

The independent assessment of scientific work by other experts in the same field before publication.

The –CO–NH– connection between neighbouring amino-acid residues in a polypeptide chain.

A person's judgement about the size or importance of a risk, which may differ from the statistical estimate.

One part in every hundred, calculated by dividing the relevant part by the whole and multiplying by 100.

The proportion of a compound's total mass contributed by a specified element, expressed as a percentage.

The fraction of a whole expressed out of 100; for oxygen in air, it can be estimated from the volume of oxygen removed divided by the initial volume of air.

The actual yield expressed as a percentage of the maximum theoretical yield.

A horizontal row of the periodic table; for the first 20 elements, its number equals the number of occupied electron shells.

The repeating pattern of similar properties among elements when they are arranged by atomic number.

The organised table in which the chemical elements are displayed.

A factor concerning an individual, such as their needs, health, circumstances, priorities or willingness to accept inconvenience or risk.

Equipment worn to reduce exposure to a hazard, such as eye protection or protective gloves selected for a particular task.

A drawing that uses sloping or receding lines, overlap and changes in position to suggest depth on a flat page.

Polyethylene terephthalate, a polymer used to make many drinks bottles and polyester fibres.

The chemical industry that uses substances obtained from crude oil or natural gas to manufacture useful products.

A liquid fuel obtained from crude oil and used in many car engines.

A numerical measure related to the hydrogen ion concentration of a solution; lower pH means a higher hydrogen ion concentration.

An electronic instrument that uses a probe to measure pH and displays a numerical value.

Mined material containing phosphate compounds; it must be treated to make its phosphorus more available to plants.

The process in which algae and plants use light energy to make glucose from carbon dioxide and water, releasing oxygen.

An electronic sensor used to measure the pH of a solution and give a numerical reading.

A numbered scale, usually from 0 to 14, that measures the acidity or alkalinity of a solution.

A graph showing how pH changes as measured volumes of an acid or alkali are added during a titration.

A layer that prevents substances such as oxygen and water from reaching a metal surface.

A change between physical states in which no new substance is produced.

A characteristic that can be observed or measured without forming a different substance, such as boiling point.

Whether a substance is a solid, liquid or gas under specified conditions.

A biological extraction method in which plants absorb metal ions from soil through their roots and concentrate them in their tissues.