Historical development of the concept of element 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. 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. Most samples of naturally occurring matter are physical mixtures of compounds. Water clearly is not an element because it consists of, and actually can be decomposed chemically into, the two substances hydrogen and oxygen these two substances, however, are elements because they cannot be decomposed into simpler substances by any known chemical process. The gaseous elements hydrogen and oxygen, for example, with quite different properties, can combine to form the compound water, which has altogether different properties from either oxygen or hydrogen. When two or more elements combine to form a compound, they lose their separate identities, and the product has characteristics quite different from those of the constituent elements. The number of possible compounds is almost infinite perhaps a million are known, and more are being discovered every day.
Elements can combine with one another to form a wide variety of more complex substances called compounds. Of the known elements, 11 (hydrogen, nitrogen, oxygen, fluorine, chlorine, and the six noble gases) are gases under ordinary conditions, two (bromine and mercury) are liquids (two more, cesium and gallium, melt at about or just above room temperature), and the rest are solids. About 20 percent of them do not exist in nature (or are present only in trace amounts) and are known only because they have been synthetically prepared in the laboratory. The Editors of Encyclopaedia Britannica General observationsĪt present there are 118 known chemical elements. For detailed information about the compounds of the elements, see chemical compound. The article also discusses the periodic law and the tabular arrangement of the elements based on it. 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. This article considers the origin of the elements and their abundances throughout the universe. Elements are the fundamental materials of which all matter is composed. SpaceNext50 Britannica presents SpaceNext50, From the race to the Moon to space stewardship, we explore a wide range of subjects that feed our curiosity about space!Ĭhemical element, also called element, any substance that cannot be decomposed into simpler substances by ordinary chemical processes.Learn about the major environmental problems facing our planet and what can be done about them! Saving Earth Britannica Presents Earth’s To-Do List for the 21st Century.Britannica Beyond We’ve created a new place where questions are at the center of learning.100 Women Britannica celebrates the centennial of the Nineteenth Amendment, highlighting suffragists and history-making politicians.
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