Hypothetical element

from Wikipedia, the free encyclopedia

A hypothetical element is a chemical element whose existence has been predicted but has not (so far) been confirmed.

In the past, substances were often accepted as new elements, which later only turned out to be compounds or manifestations of already known elements. Nowadays, on the other hand , the properties of elements that do not occur in nature but can be artificially produced in the future are systematically predicted from atomic physics , nuclear physics and the periodic table of elements based on them .

Historical hypothetical elements

In the 19th century, astrospectroscopy in particular provided numerous hypothetical elements. In 1864 , William Huggins discovered bright lines in the Cat's Eye Nebula . As a possible explanation, he suggested the existence of a hypothetical element, the nebulium . It was not until 1927 that Ira S. Bowen identified the lines as forbidden transitions of the known elements oxygen , nitrogen , helium and neon .

During the solar eclipse of 1869, astronomers discovered unexpected spectral lines in the solar corona . Similar to the nebulium, these unusual spectral phenomena were attributed to the hypothetical element coronium . But here, too, we are dealing with highly ionized known elements, namely [ Fe  XIV]. Similar lines have been observed near Earth and attributed to the element Geocoronium . However, Bengt Edlén discovered in the 1950s that these lines consist of radiation-emitting nitrogen in the upper atmosphere.

In 1904, Dmitri Iwanowitsch Mendeleev attempted a chemical explanation of light ether and predicted the existence of an element newtonium , which belongs to the group of noble gases and, with a relative atomic mass of 0.17, should precede hydrogen in the periodic table.

Other hypothetical elements were archonium and protofluor . Aside from their names, chemists knew little about these hypothetical elements. Analogous to the discovery of helium on the basis of unexpected lines in the spectrum of the sun and only afterwards also on earth, these hypothetical elements were classified between the elements hydrogen and helium in the periodic table.

However, this classification according to the relative atomic mass turned out to be unreliable. In the course of the development of the periodic table, the classification of elements according to their relative atomic mass was replaced by a classification according to their nuclear charge .

Today's hypothetical elements

In the second half of the 20th century it became possible to artificially create extremely heavy elements ( transuranic elements ) that did not exist in nature . The currently heaviest detected element is Oganesson with the ordinal number 118, all heavier elements from the Ununennium on must therefore currently be considered hypothetical elements.

See also

Web links

Individual evidence

  1. ↑ Eric R. Scerri, John Worrall : Prediction and the periodic table. In: Studies in history and philosophy of science, part A. Vol. 32, No. 3, 2001, ISSN  0039-3681 , pp. 407-452 ( doi : 10.1016 / S0039-3681 (01) 00023-1 ).