- Selenium was discovered in 1818 by the famous scientist Berzelius. The first identified selenium sample was discovered accidentally, as it was thought to be a sample of tellurium. Careful study of the element yielded findings inconsistent with any known element, so selenium was then officially discovered.
- There are six isotopes of selenium present in nature, ranging from selenium-74 to selenium-82. There exist even more radioactive isotopes that are created artificially using particle bombardment techniques. The main radioactive isotope used in industry is selenium-75, which is a radioactive tagging tool that identifies the location of selenium in the body.
- Selenium is important in normal bodily function because it acts as an antioxidant. In normal oxygen metabolism and biological processes, free radicals are produced. These chemical species are highly reactive and tend to bind to DNA, sometimes leading to mutations. Selenium, however, binds to these radicals before they are able to do harm to genetic code.
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Selenium can be added to glass due to its antagonistic effect on the green color from iron; it cancels it out, leaving glass colorless and transparent. If not in the presence of iron, however, selenium can also be used to enrich the glass with a deep red color.
The element is also used in copying and printing technology, as well as in solar cells. Each of these applications of selenium is based on its ability to aid in the conversion of light to usable electricity. -
Selenium melts at 217°C and boils at about 685°C. The molar mass of selenium is 78.96 g/mol. It is considered a nonmetal.
Although it is a nonmetal, selenium is solid at 298K and appears gray and metallic like an alkali or alkaline earth metal would. It is a semiconductor, which underscores its importance in the electrical industry. - Although selenium is necessary for good health, it can be detrimental if too much is ingested. Usually, excessive selenium intake is most common in areas with high selenium soil content. It is dangerous in excess because of its chemical similarity to arsenic. Brazil nuts in particular are recognized as being extremely rich in selenium, so moderation should be practiced in their consumption. Insufficient selenium intake is also unfavorable because it may weaken the development and strength of muscles.
