What is an element?

The elements are sometimes called the building blocks of the Universe because everything in the Universe – including ourselves – is made of them. The nucleus of each element consists of atoms with the same number of protons. Each element is unique, although elements can exist in different forms – for example, carbon may be soft graphite or hard diamond. Elements cannot be broken down into any other substance. There is about 118 elements altogether, and 91 occur naturally on Earth. Others can be created artificially in laboratories, but in minute quantities and they have very short life spans of only thousandths of a second. Each element is also known by a one- or two- letter symbol as well as its name. Examples are Fe for Iron and Na for sodium. A chemical compound is a combination of two or more elements linked together, which can be broken down again into their constituent parts but no further.