Chemistry

Chemistry is the science of matter, its composition, structure, properties and the changes it undergoes during reactions. All matter is built from atoms, each consisting of a small dense nucleus of protons and neutrons surrounded by electrons. The way electrons are arranged determines how atoms bond together to form molecules and compounds, and the periodic table organises the chemical elements by atomic number so that those with similar properties fall into the same columns.

The subject is broadly divided. Organic chemistry studies compounds based on carbon, whose ability to form long chains and rings gives rise to an enormous variety of molecules, including amines and the large repeating-unit molecules called polymers from which plastics and many natural materials are made. Inorganic chemistry deals with the remaining elements and their compounds, such as metals, minerals and salts. Many chemical processes can be understood in terms of acids and bases, which react together and are measured on the pH scale.

Reactions involve the rearrangement of atoms and the transfer or sharing of electrons. Electrochemistry examines reactions that involve the movement of electrons through a circuit, the principle behind batteries and electroplating. Modern chemistry relies heavily on accumulated data, and chemical databases catalogue the structures, properties and reactions of millions of substances, supporting research in medicine, materials science and industry.

Frequently asked questions

What is the difference between organic and inorganic chemistry?

Organic chemistry studies carbon-based compounds, which form a huge range of molecules. Inorganic chemistry covers the other elements and their compounds, such as metals and salts.

How is the periodic table organised?

Elements are arranged by increasing atomic number into rows and columns so that those with similar chemical properties line up in the same vertical group.

What is a polymer?

A polymer is a large molecule built from many small repeating units joined together. Plastics, proteins and natural rubber are all examples of polymers.