Chemistry key terms

Room temperature and pressure: for AQA gas-volume calculations, $20\,°\text{C}$ and a pressure of 1 atmosphere.

The corrosion of iron or steel when both oxygen from the air and water are present.

Protection in which a more reactive metal corrodes instead of the metal being protected.

An ionic compound formed when the hydrogen ions of an acid are replaced by positive ions, such as metal ions.

A limited quantity of material taken for analysis and intended to represent the larger body of material.

The number of independent observations, objects, specimens or experimental units included in an investigation.

A hydrocarbon containing only single bonds between its carbon atoms.

A solution in which no more solute can dissolve at that temperature.

A scale showing how large or small something is by comparing its dimensions with a known length or with other objects.

A number showing how many times as large one value is as another; it is calculated as new value divided by original value for the same quantity.

The sharing of scientific questions, methods, evidence, conclusions and significance in a form suited to its intended recipients.

A development in scientific knowledge, understanding or methods.

A scientific account that connects evidence and accepted ideas to explain how or why something happened.

A systematic process of posing questions, gathering and analysing evidence, considering alternative explanations and communicating conclusions.

A simplified representation used to describe and explain scientific observations; it may be changed or replaced when new evidence does not fit it.

A measurable property written as a numerical value with an appropriate unit, such as a time of 30 s.

A question that could, at least in principle, be investigated using observations, measurements, evidence and scientific reasoning.

The logical scientific explanation connecting evidence to a finding or conclusion.

A proposed explanation of events or observations that can be assessed using evidence.

Discarded metal that can be collected and processed for recycling.

Particles of solid material that settle and accumulate, often on the floor of a body of water.

Rock formed when layers of sediment accumulate and become compacted or cemented together.

The settling of suspended solid particles under gravity.

A life cycle assessment that includes only selected stages or environmental effects.

The ability of a method to detect or measure a very small amount of a substance.

A device that detects a substance or a change in its surroundings and produces a response that can be measured.

Waste water containing human waste and other material carried away from homes and other buildings.

The thick, solid-rich material that settles at the bottom of a sedimentation tank.

A pair of electrons shared between two atoms in a covalent bond.

A pair of electrons associated with both bonded atoms rather than with only one of them.