Keep on studying while the schools are closed! Click here to save 50% on our revision guides!

A-Z Chemistry definitions for use with A-Level Chemistry

Our database of chemistry definitions provides key information and a summary of many chemistry terms, covering them in enough detail to help you fully understand the terms in preparation for your A-Level Chemistry exams.

Looking for revision notes that are specific to the exam board you are studying? If so, click the links below to view our condensed, easy-to-understand revision notes for each exam board, practice exam question booklets, mindmap visual aids, interactive quizzes, PowerPoint presentations and a library of past papers directly from the exam boards.

Optical Isomerism

Key Information & Summary Two compounds with the same brute formula are called isomers. There are different types of isomers: homomers, stereoisomers, constitutional isomers. In particular a stereocenter or stereogenic center is any point in a molecule bearing groups, such that an interchanging of any two groups leads to a stereoisomer. The presence of the ...

Read article →Optical Isomerism

Organic Analysis

Key Information & Summary The first operation is the determination of the chemical-physical properties: the melting point of the solid compounds, the boiling point of the liquid compounds. The qualitative research of the elements follows, trying to discover if, in addition to carbon and hydrogen, there are other elements such as nitrogen, sulfur, halogens, etc. ...

Read article →Organic Analysis

Reaction Of Ions In Aqueous Solutions

Key Information & Summary A solvent is a liquid that dissolves a solid, liquid or gaseous compound called solute, giving rise to a solution. The solvation (or dissolution) in chemistry is interaction between solute and solvent that brings the single dissolved solute molecules to surround themselves with solvent molecules. If the solvent responsible for solvation ...

Read article →Reaction Of Ions In Aqueous Solutions

Axial and Equatorial

Facts, Summary & Definition Axial and equatorial are types of bonds found in the chair conformation of cyclohexane The chair conformation is the most stable conformation of cyclohexane Axial positions are perpendicular to the plane of the ring and equatorial positions are around the plane of the ring The bond angles in this conformation are ...

Read article →Axial and Equatorial

Balancing Redox Reactions

Facts, Summary & Definition In redox reactions, one reactant is oxidised, and one is reduced The most common method of balancing redox reactions is the ion-electron method (which can also be called the half-reaction method) There are many steps in balancing a redox reaction, and all must be done in the correct order to give ...

Read article →Balancing Redox Reactions


Facts, Summary & Definition Atoms are the smallest unit of matter and combine to form molecules They contain protons, neutrons, and electrons More than 99% of an atom is empty space but electrons make atoms repel The number of protons in an atom determines its atomic number The number of protons and neutrons determines its ...

Read article →Atoms

Atomic Absorption Spectroscopy

Facts, Summary & Definition AAS is used to measure the concentrations of elements in a sample It is based on the principle that the atoms of each element absorb a specific and unique frequency of radiation The concentration of an element in a sample can be calculated using a calibration curve What is atomic absorption ...

Read article →Atomic Absorption Spectroscopy


Facts, Summary & Definition Anisotropy is the property of a substance to show variations in physical properties along different molecular axes These physical properties can be absorbance, electrical conductivity, and thermal conductivity etc. Anisotropic materials are the opposite of isotropic materials What is anisotropy? Anisotropy is defined as the property of a substance to show ...

Read article →Anisotropy


Facts, Summary & Definition An amphoteric molecule is a molecule that can act and both a base and an acid All amphoteric molecules contain a hydrogen atom Water, amino acids, hydrogen carbonate ions, and hydrogen sulphate ions are all amphoteric What is amphoterism? An amphoteric molecule is a molecule that can act as both a ...

Read article →Amphoterism

Ambidentate Ligands

Facts, Summary & Definition Ambidentate ligands are a type of ligand which can bond to the central atom in two places, but not at the same time SCN- and NO2- are good examples of ambidentate ligands What are ambidentate ligands? To understand ambidentate ligands, one must first understand what a ligand is. A ligand is ...

Read article →Ambidentate Ligands