What is an Elements?

A substance that can't be changed into a simpler form by chemical reactions. Its characteristics are determined by the number of protons in its atoms, which determine the type of electrons that orbit them. Each element has a unique weight and shape that dictates its physical properties. It may also have isotopes, which have different numbers of protons and thus have differing chemical properties.

In Greek thought, there were four elements: fire, air, water and earth. Aristotle thought that all other things could be broken down into these four and that all objects have certain characteristic properties that reflect their elemental composition. This was the basic idea behind chemistry. The modern concept of an element came from Robert Boyle and Antoine Lavoisier in the 1600s, who defined a pure substance as one that cannot be broken down further. They also classified them into metallic and nonmetallic, with the latter including metals such as mercury, silver and gold.

The 118 known elements have a wide variety of fascinating physical and chemical properties. The majority (92, to be precise) are found in nature, and the rest have been produced synthetically in the laboratory. Elements can combine with each other to create a wide range of more complex substances called compounds.

Compounds are materials that contain more than one element and are kept together by chemical bonds. For example, table salt is made up of sodium ions (which are bonded to chlorine atoms) and other elements. Water and carbon dioxide are also examples of compounds. The types of bonds that hold the elements together can vary - covalent or ionic.