Edexcel GCSE Chemistry key terms

Describes a substance from which its water of crystallisation has been removed.

A compound containing no water within its crystal structure.

A negatively charged ion, formed when an atom or group of atoms gains one or more electrons.

The positive electrode in electrolysis, where particles lose electrons and oxidation occurs.

A result that differs markedly from the pattern of the other results.

Describes a substance dissolved in water; it is represented by the state symbol $(aq)$.

A solution in which an acid is dissolved in water and can provide hydrogen ions, H⁺.

A solution in which water is the solvent.

An ending usually showing that the negative ion contains oxygen bonded to another element, as in nitrate, carbonate or sulfate.

The layer of gases surrounding Earth.

The smallest particle of an element that can exist while retaining the properties of that element.

The percentage of the mass of the reactants that is incorporated into the desired product, as determined from the balanced equation.

A proposed description of an atom that can be changed when new evidence is found.

The number of protons in the nucleus of an atom.

The approximate distance from the centre of an atom to the extent of its electron cloud.

The number of specified particles in one mole: 6.02 × 10²³ mol⁻¹ at GCSE precision.

At the same temperature and pressure, equal volumes of gases contain equal numbers of gas particles.

An equation that represents a chemical reaction using chemical formulae and has the same number of atoms of each element on both sides.

A chemical equation with the same number of atoms of each element on both sides.

An equation with equal numbers of atoms of each element on its two sides.

A model in which balls represent atoms and sticks represent bonds, making the arrangement of atoms easier to see.

A layer that prevents oxygen or water from reaching the iron beneath it.

A substance that reacts with an acid to form a salt and water only.

The starting line on chromatography paper where samples are placed.

The common basis on which products are compared, such as one bag, one use or the entire working life of an appliance.

Manufacture in which a fixed quantity of product is made at one time before the equipment is prepared for another run.

Containing only two different elements.