Seawater, for example, is a mixture of water and a large number of other compounds, the most common of which is sodium chloride, or table salt.
Mixtures differ from compounds in that they can be separated into their component parts by physical processes; for example, the simple process of evaporation separates water from the other compounds in seawater.
This article considers the origin of the elements and their abundances throughout the universe.
The geochemical distribution of these elementary substances in the Earth’s crust and interior is treated in some detail, as is their occurrence in the hydrosphere and atmosphere.
The ancient Greek philosophers Thales, Anaximenes, and Heracleitus each suggested that all matter is composed of one essential principle—or element.
Thales believed this element to be water; Anaximenes suggested air; and Heracleitus, fire.
They are mentioned in the Bible and in an early Hindu medical treatise, the .Sixteen other elements were discovered in the second half of the 18th century, when methods of separating elements from their compounds became better understood.Eighty-two more followed after the introduction of quantitative analytical methods.Chemical element, also called element, any substance that cannot be decomposed into simpler substances by ordinary chemical processes.Elements are the fundamental materials of which all matter is composed.