AQA GCSE Chemistry key terms

A Group 7 non-metal whose atoms have seven electrons in their outer shell.

The resistance of a material to scratching, cutting or permanent indentation.

A family of compounds with the same functional group and similar chemical properties; successive members differ by CH₂.

A substance that contains water as part of its crystal structure.

A compound containing carbon and hydrogen atoms only.

A positively charged ion, written $\mathrm{H^+}$, produced by acids in aqueous solution.

A prediction that can be tested by an investigation.

Liquids that do not mix and form separate layers.

An unwanted substance mixed with the substance being examined.

Combustion in a limited supply of oxygen, which can produce carbon monoxide, solid carbon and unburned fuel as well as water.

An electrode that conducts electricity without reacting with the electrolyte or products.

Electromagnetic radiation emitted by warm objects; Earth’s warmed surface emits long-wavelength infrared radiation.

A substance that does not dissolve, or dissolves only to a negligible extent, in a particular solvent.

A method that uses measuring equipment to detect, identify or measure chemical substances.

An attraction acting between separate molecules; it is weaker than the covalent bonds within the molecules.

An atom or group of atoms with an overall electrical charge because it has gained or lost electrons.

The strong electrostatic attraction between oppositely charged ions.

A strong electrostatic attraction between oppositely charged ions.

A chemical equation showing only the ions that take part in the reaction, with atoms and electrical charge balanced.

The formation of ions from neutral particles when a substance is dissolved or reacts.

An atom of an element that has the same number of protons as its other atoms but a different number of neutrons.

Atoms of the same element with the same number of protons but different numbers of neutrons.

The proportion of an element's atoms that are a particular isotope, often expressed as a percentage.

A repeating three-dimensional arrangement of particles in a solid.

The principle that no atoms are made or lost during a chemical reaction, so the total mass of all the products equals the total mass of all the reactants.

A solution containing dissolved substances that have been washed or released from a solid material.

A qualitative rule stating that when the conditions of a system at equilibrium are changed, the system shifts in the direction that counteracts the change.

An assessment of the environmental impact of a product across the stages of its life, from obtaining raw materials to its end-of-life treatment.