AQA GCSE Chemistry key terms

The mixture of gases surrounding the Earth.

The smallest particle of an element that can take part in chemical reactions, consisting of a nucleus surrounded by electrons.

The percentage of the total relative mass of the reactants that becomes the desired useful product, as shown by a balanced equation.

The number of protons in the nucleus of an atom; it identifies the element.

A historical measure of an element’s atomic mass relative to that of another atom; it corresponds broadly to what is now called relative atomic mass.

The number of specified particles in one mole, with the value $6.02 \times 10^{23}\ \text{mol}^{-1}$.

A symbol equation containing the same number of atoms of each element on both sides.

A reaction equation with 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 insoluble white compound, $\mathrm{BaSO_4}$, formed when barium ions react with sulfate ions in solution.

A protective layer that keeps substances in the environment from reaching the material beneath it.

A particle that accepts a proton in a proton-transfer reaction.

Two or more cells connected together, normally in series to provide a greater total voltage.

A tendency for the selection or presentation of evidence to favour a particular conclusion.

A compound made from two different elements.

The variety of different living organisms in an area or across Earth.

A biological extraction method in which bacteria help produce a leachate solution containing dissolved metal compounds.

The chemical removal of colour from a substance.

The change of state from a liquid to a gas throughout the liquid, with bubbles forming.

The temperature at which a liquid boils and changes to a gas throughout the liquid.

The energy required to break one mole of a specified type of chemical bond; it is usually given in kJ/mol.

A spherical fullerene molecule containing 60 carbon atoms, with the formula C₆₀.

Material present on an ordinary large scale, such as a lump or a powder containing a very large number of atoms.

A property of a large sample of material, such as its melting point, rather than a property of one individual atom or molecule.

A graduated tube with a tap that delivers and measures a variable volume of solution.

A wooden splint that has been lit and still has a flame.

A product formed alongside the desired product.

A graph relating a measured signal to known concentrations, used to find the concentration of an unknown sample.