An octatomic element is a
chemical element
A chemical element is a species of atoms that have a given number of protons in their nuclei, including the pure substance consisting only of that species. Unlike chemical compounds, chemical elements cannot be broken down into simpler sub ...
that, when
standard conditions for temperature and pressure
Standard temperature and pressure (STP) are standard sets of conditions for experimental measurements to be established to allow comparisons to be made between different sets of data. The most used standards are those of the International Union o ...
is stable, is in a configuration of eight atoms grouped together. The canonical example is
sulfur
Sulfur (or sulphur in British English) is a chemical element with the symbol S and atomic number 16. It is abundant, multivalent and nonmetallic. Under normal conditions, sulfur atoms form cyclic octatomic molecules with a chemical formula ...
, S
8,
but red
selenium
Selenium is a chemical element with the symbol Se and atomic number 34. It is a nonmetal (more rarely considered a metalloid) with properties that are intermediate between the elements above and below in the periodic table, sulfur and tellurium, ...
is also an octatomic element stable at room temperature.
Octaoxygen
Octaoxygen, also known as boxygen, is an allotrope of oxygen consisting of eight oxygen atoms, also known as ε-oxygen or red oxygen. This allotrope forms above at pressures greater than 17 GPa.
Preparation and properties
As the pressure of o ...
is also known, but it is extremely unstable.
See also
*
Diatomic element
Diatomic molecules () are molecules composed of only two atoms, of the same or different chemical elements. If a diatomic molecule consists of two atoms of the same element, such as hydrogen () or oxygen (), then it is said to be homonuclear. Ot ...
References
Molecules
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