Chemistry key terms

A numerical measurement accompanied by an appropriate unit.

The transfer of energy by electromagnetic waves.

The distance from the centre of a sphere or approximately spherical object to its edge.

Unpredictable variation that causes repeated measurements to differ from one another.

The difference between the highest and lowest retained measurements in a set.

A vertical line on a graph extending from the lowest to the highest repeat measurement at one value of the independent variable.

Able to produce a result quickly.

How quickly reactants are used up or products are formed.

A comparison showing the relative amounts of two or more quantities. In a balanced chemical equation, the coefficients give the ratio of amounts in moles.

The scientific purpose and reasoning behind an investigation, including what is being tested and why the chosen approach can provide relevant evidence.

A naturally occurring material from which useful products are made; metal ores are finite raw materials.

The substances obtained and processed to make a product.

A starting substance that is changed during a chemical reaction.

The substances present at the start of a chemical reaction.

The calculated amount of reactant needed or product formed when the reacting quantities follow a balanced equation.

The ratio of the masses of substances that react or form, calculated from a balanced equation and their relative formula masses.

The arrow pointing from reactants to products; it can be read as “produces” or “forms”.

A factor deliberately set or changed during a reaction, such as temperature, concentration, gas pressure or the surface area of a solid.

Factors such as temperature and the presence or removal of substances that affect how a reaction proceeds.

A sequence of chemical reactions used to make a specified product.

A diagram showing the relative energies of the reactants and products and the activation-energy barrier between them.

The amount of a reactant used or product formed per unit time.

The reacting substances being considered when tracking an energy transfer.

A measure of how readily a substance undergoes chemical reactions.

A list of elements arranged in order of reactivity, usually from most reactive to least reactive.

A chemical added to a sample to produce an observable reaction that helps identify a substance.

Changing the form of an equation without changing the relationship it represents.

Changing the form of an equation without changing the relationship it expresses.

Rewriting an equation to make a different variable its subject without changing the relationship it expresses.

A judgement that answers the question being investigated and is supported by relevant evidence and scientific reasoning.