OCR GCSE Chemistry A key terms

Checking or adjusting an instrument against reference samples with known values so that its readings are reliable.

A graph made using samples of known concentration, used to estimate the concentration of an unknown sample from a measured signal.

An ionic compound containing a positive ion and the carbonate ion, CO₃²⁻.

A method of preventing some carbon dioxide from entering the atmosphere by capturing it from emissions and storing it deep underground.

A colourless, odourless, toxic gas with the formula CO, produced when carbon-containing fuels burn incompletely.

A hollow, cylindrical structure of bonded carbon atoms that is very narrow compared with its length.

An organic compound containing the –COOH functional group.

A substance that increases the rate of a chemical reaction without being used up overall.

The negative electrode in an electrolytic cell, where positive ions gain electrons.

A positively charged ion.

The difference between two values, commonly written using the Greek letter delta, $\Delta$.

The difference between the final and initial values of a measured quantity.

A physical change between solid, liquid and gas in which the chemical identity of a substance remains unchanged.

A strong electrostatic attraction that holds atoms or ions together within a substance.

A device in which chemical reactions produce a potential difference between two electrodes.

A change in which one or more new substances form because atoms or ions from the reactants are rearranged into different particles or structures.

A representation of a substance that shows its elements and how many atoms of each are present, or their simplest ratio.

A characteristic describing how a substance reacts and what new substances it forms.

A drawing or model that stands for a chemical structure while showing selected features of it.

Any atom, molecule, ion or formula unit represented in a chemical calculation or equation.

The arrangement of atoms and the bonds connecting them in a substance.

A one- or two-letter abbreviation for an element, beginning with a capital letter.

The pattern of separated components produced by chromatography.

A separation technique in which the components of a mixture move at different rates because they distribute differently between a stationary phase and a mobile phase.

The long-term pattern of weather, including temperature and rainfall, in a place or across the Earth.

Long-term changes in climate, including warming and changes in rainfall and extreme weather.

Action taken to limit climate change by reducing greenhouse-gas emissions or increasing their removal from the atmosphere.