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2025-02-20T01:44:54Z

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			File:Selenium trigonal.jpg\|Selenium
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			File:Polyselenide.svg\|Selenium
			File:Luna statue.jpg\|Selenium
			File:Selenium in sandstone Westwater Canyon Section 23 Mine Grants, New Mexico.jpg\|Selenium
			File:Selenium paradox.jpg\|Selenium
			File:Se dose-response curve for juvenile salmon mortality - percent scale.jpg\|Selenium
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Prab: CSV import

2024-12-31T12:33:09Z

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Kondreddy Naveen at 10:10, 28 March 2023

2023-03-28T10:10:01Z

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[[File:Selen 1.jpg|thumb|Selen_1]]

{{Infobox element
| name = Selenium
| image name = Selen 1.jpg
| alt = A photo of a selenium crystal.
| caption = Selenium crystal
| pronunciation = {{IPA|/səˈliːniəm/}}
| element category = Nonmetal
| symbol = Se
| atomic number = 34
| appearance = Black, red, and gray (not pictured) allotropes
| standard atomic weight = 78.96(3)
| electron configuration = [Ar] 3d10 4s2 4p4
| per shell =
1st: 2
2nd: 8
3rd: 18
4th: 6
| physical properties = yes
| phase = solid
| sublimation point = 958 K (685 °C, 1265 °F)
| boiling point = 958 K (685 °C, 1265 °F)
| density near rt = 4.81 g/cm3
| when liquid, at m.p. = 4.39 g/cm3
| triple point = 494 K, 101 kPa
| heat of fusion = 6.69 kJ/mol
| heat of vaporization = 95.48 kJ/mol
| molar heat capacity = 25.363 J/(mol·K)
| vapor pressure = P (Pa) 1 10 100 1 k 10 k 100 k
at T (K) 496 547 616 712 853 1057
| atomic properties = yes
| oxidation states = 6, 5, 4, 3, 2, 1, −1, −2 (an amphoteric oxide)
| electronegativity = 2.55
| ionization energies =
| 1st: 941.0 kJ/mol
| 2nd: 2045 kJ/mol
| 3rd: 2973.7 kJ/mol
| covalent radius = 120±4 pm
| van der Waals radius = 190 pm
| spectral lines of selenium
| other properties = yes
| natural occurrence = primordial
| crystal structure = {{nowrap|[[Hexagonal crystal family|Hexagonal]]}} close-packed (hcp)
| magnetic ordering = diamagnetic
| CAS Number = 7782-49-2
| history =
| named by = Jöns Jakob Berzelius
| discovery = Jöns Jakob Berzelius and Johan Gottlieb Gahn (1817)
}}

Selenium is an element needed by the [[body]] only in very small amounts that helps maintain [[tissue]] elasticity.

{{intro}}
Selenium is present in biologic systems in amino acids, such as selenocysteine and selenomethionine, usually as a part of proteins, which are referred to as selenoproteins. While selenium is present in many important enzyme systems, deficiency of selenium is rare.
'''Selenium''' is a nonmetal chemical element with the symbol Se and atomic number 34. It is a rare element, found in the Earth's crust at an average concentration of just 0.05 parts per million. Selenium is a member of the chalcogen group on the periodic table, along with sulfur and tellurium.

==History==
Selenium was discovered in 1817 by Jöns Jakob Berzelius and Johan Gottlieb Gahn. It was named after the Greek word "σελήνη" (selene), which means "moon", because of its similarity to tellurium, which had been named after the Latin word "tellus", meaning "earth".

==Occurrence==

[[File:Selenium pathways and transformations.png|Selenium_pathways_and_transformations]]

Selenium is a relatively rare element, found in the Earth's crust at an average concentration of just 0.05 parts per million. It is found in a number of minerals, including the sulfides pyrite and galena, and the selenides naumannite and clausthalite.

Selenium is also present in someplants, particularly in those grown in soil with high selenium content. It is an essential trace element for many organisms, including humans, but can be toxic in large amounts.

==Properties==
Selenium has several allotropes, including black, red, and gray forms. It is a nonmetal with properties that are intermediate between those of metals and nonmetals. It is a semiconductor, meaning it can conduct electricity under certain conditions, and has a wide range of uses in electronics and other industries.

Selenium is also important for the human body, as it is a necessary nutrient in small amounts. It is involved in the production of thyroid hormones and has antioxidant properties. However, like many trace elements, it can be toxic in large amounts.

==Uses==
Selenium has a variety of uses in industry and technology. It is a key ingredient in many types of glass, including glass used in the production of photovoltaic cells. It is also used in the production of semiconductors, including the production of certain types of solar cells.

In addition, selenium has uses in the metallurgical industry, as a component of stainless steel and other alloys. It is also used in the production of pigments and as a catalyst in chemical reactions.

Selenium is also important for the human body, and is used in some dietary supplements. However, it can be toxic in large amounts and should be consumed only in the recommended amounts.

{{def}}
[[Keshan disease]], an endemic cardiomyopathy affecting children and young women in parts of China, has been linked to selenium deficiency, although other nutritional deficiencies or local factors may also may a role.

{{toxicity}}
Excess selenium exposure can cause cirrhosis in laboratory animals, but toxicity in humans has been linked largely to skin, hair and nail changes. An outbreak of possible selenium toxicity due to a nutritional supplement was marked by nausea, diarrhea, irritability, fatigue, neuropathy, hair loss and nail changes, without liver test abnormalities.

{{trace elements}}
{{stubd}}

==References==
{{Reflist}}

==External links==
{{Commons|Selenium}}

{{Periodic table}}
[[Category:Chemical elements]]
[[Category:Nonmetals]]
[[Category:Chalcogens]]

Selenium - Revision history

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Kondreddy Naveen at 10:10, 28 March 2023