Glossary

Atomic number

The number of protons in the nucleus of an atom.

Catalyst

A substance that increases the rate of a chemical reaction. The catalyst itself does not undergo a permanent change.

Chemical formula

A representation of the relative proportions of elements in a compound using chemical symbols. For example, the chemical formula of the nitrogen molecule is N₂, where N is the chemical symbol for nitrogen and the subscript 2 tells you how many nitrogen atoms are in the molecule.

Chemical equation

Representations of chemical reactions. A chemical equation must be balanced, so the number of atoms on the left-hand side of the equation is equal to the number of atoms on the right-hand side.

Electrolysis

A chemical reaction driven by electricity.

Electrode

The conducting points through which an electric current enters or leaves something, for example, a battery or electrolysis reaction

Element

A single substance that cannot be split into a simpler substance

Functional Group

An atom, or a group of atoms, that has similar chemical properties whenever it occurs in different compounds. Functional groups define the characteristic physical and chemical properties of families of organic compounds

Natural elements

Elements up to 94 which are found in nature (e.g. obtained from minerals). Elements with higher atomic number are synthesised in the laboratory

Organic compound

Compounds based on carbon.

Product

The compound(s) formed as a result of a chemical reaction.

Reactant

The starting materials in a chemical reaction.

Relative atomic mass

A set of numbers, one for each chemical element. The ratio between the numbers for any two elements being equal to the ratio between the average masses of their atoms. The scale of numbers is fixed by assigning a value to one particular type of atom carbon-12, , where the relative atomic mass of carbon is taken as exactly 12 and values for other atoms are defined relative to this.

Solution

A liquid mixture made up of a solute dissolved in a solvent. The solvent is present in the largest amount in the mixture .