• Chemical element
• History
• description
• Nomenclature
• Specific chemical elements
• General chemical symbols
• Isotope symbols

Chemical element

A chemical element, or element for short, is a type of atom that is defined by its atomic number; that is, by the number of protons in its nucleus. The term is also used to refer to a pure chemical substance composed of atoms with the same number of protons.

Common examples of elements are hydrogen, nitrogen, and carbon. In total, 117 elements have been observed as of 2007, of which 94, i.e. plutonium and below, occur naturally on Earth. Elements with atomic numbers greater than 82 (i.e,. bismuth and those above), are inherently unstable and undergo radioactive decay. In addition, elements 43 and 61 (technetium and promethium) have no stable isotopes, and also decay. However, the unstable elements up to atomic number 94 with no stable nuclei are found in nature as a result of the natural decay processes of uranium and thorium.

All chemical matter consists of these elements. New elements are discovered from time to time through artificial nuclear reactions