OCR GCSE Chemistry A key terms

The dissolved substance in a solution.

A uniform mixture formed when a solute dissolves in a solvent.

The liquid that dissolves a solute.

The furthest point reached by the solvent on a chromatogram.

A chemical entity, such as an ion, molecule or element, whose identity can be inferred from characteristic test results.

The objects being counted, such as atoms, molecules, ions, electrons or formula units.

A dissolved ion that remains chemically unchanged during a reaction and is omitted from the ionic equation.

A measurement unit raised to the power 2, used for area; for example, cm².

A way of writing a number as a value from 1 up to but not including 10, multiplied by a power of ten.

A solution whose concentration is known accurately and which is used to determine another solution's concentration.

The physical form of a substance, such as solid, liquid or gas.

A symbol written after a chemical formula to show whether the substance is solid (s), liquid (l), gas (g) or dissolved in water (aq).

The phase that remains fixed in place while chromatography is carried out.

A family of alloys based mainly on iron and carbon; some steels also contain other elements.

Resistance to deformation under a force; a stiffer material changes shape less under the same conditions.

The large number written before a formula in a balanced equation; it gives the reacting ratio and multiplies the formula's mass contribution.

The whole-number numbers placed before formulae in a balanced equation; they show the reacting mole ratio.

The whole-number relationship between the amounts in moles of substances that react, obtained from the coefficients in a balanced equation.

The quantitative ratio in which substances react or are produced, shown by the coefficients in a balanced chemical equation.

A substance that ionises completely in water to produce hydrogen ions, $\text{H}^+(aq)$.

A soluble base that dissociates completely in water to produce hydroxide ions, $\text{OH}^-(aq)$.

The arrangement of atoms and bonds in a molecule. It can be written in condensed form or drawn as a fully displayed formula.

A drawing or model used to show selected features of a chemical structure.

The variable written alone on one side of a formula and calculated from the other variables.

The variable written alone on one side of an equation; the equation is arranged to calculate this variable.

A small number within a chemical formula that shows how many atoms of the preceding element are present.

Replacing variables with known numerical values.