Selenium (Se)
nonmetalSolid
Standart Atom Ağırlığı
78,971 uElektron dizilimi
[Ar] 4s2 3d10 4p4Erime noktası
220,5 °CKaynama noktası
684,85 °CYoğunluk
4809 kg/m³Yükseltgenme basamakları
−2, −1, 0, +1, +2, +3, +4, +5, +6Elektronegatiflik (Pauling)
2,55İyonlaşma enerjisi (1.)
9,752368 eVKeşif yılı
1817Atom yarıçapı
115 pmAyrıntılar
Selenium is a chalcogen between sulfur and tellurium, with chemistry that commonly parallels both. It is a trace element required by many organisms because it is incorporated into selenoproteins, yet the margin between nutritional requirement and toxicity is narrow. Industrially, selenium is valued for its semiconductor and photoconductive behavior, its red color in glass, and its role in metallurgy and specialty chemicals.
Selenium exists in several allotropic forms, although three are generally recognized. Selenium can be prepared with either an amorphous or a crystalline structure. The color of amorphous selenium is either red (in powder form) or black (in vitreous form). Crystalline monoclinic selenium is a deep red; crystalline hexagonal selenium, the most stable variety, is a metallic gray.
Selenium exhibits both photovoltaic action, where light is converted directly into electricity, and photoconductive action, where the electrical resistance decreases with increased illumination. These properties make selenium useful in the production of photocells and exposure meters for photographic use, as well as solar cells. Selenium is also able to convert a.c. electricity to d.c., and is extensively used in rectifiers. Below its melting point, selenium is a p-type semiconductor and has many uses in electronic and solid-state applications.
Elemental selenium has been said to be practically nontoxic and is considered to be an essential trace element; however, hydrogen selenide and other selenium compounds are extremely toxic, and resemble arsenic in their physiological reactions.
The name derives from the Greek Selene, who was the Greek goddess of the Moon because the element is chemically found with tellurium (Tellus was the Roman goddess of the Earth). Selenium was discovered by the Swedish chemist Jöns Jacob Berzelius in 1817, while trying to isolate tellurium in an impure sample.
Selenium was discovered by Jöns Jacob Berzelius, a Swedish chemist, in 1817 after analyzing an impurity that was contaminating the sulfuric acid (H2SO4) being produced at a particular factory in Sweden. Originally believing the material was tellurium, Berzelius eventually realized that it was actually a previously unknown element. Selenium occurs in minerals such as eucairite (CuAgSe), crooksite (CuThSe) and clausthalite (PbSe), but these minerals are too rare to use as a major source of selenium. Today, most selenium is obtained as a byproduct of refining copper.
From the Greek word Selene, moon. Discovered by Berzelius in 1817, who found it associated with tellurium (named for the earth).
Elemental selenium has several allotropes. The most familiar macroscopic forms are red amorphous selenium and gray trigonal selenium, a brittle, metallic-looking solid that is the most stable form at ordinary conditions. Black vitreous selenium can form by rapid cooling from the melt.
Selenium has been used in photocells, light meters, rectifiers, and xerographic photoreceptors, although many of these applications have been reduced by silicon and organic photoconductors. It is still used to decolorize or color glass, producing ruby-red glasses and counteracting green iron tints. Small additions improve machinability in some copper and steel alloys. Selenium compounds are used in pigments, rubber vulcanization chemistry, antifungal shampoos, and as reagents in organic synthesis.
Selenium's resistance to the flow of electricity is greatly affected by the amount of light shining on it. The brighter the light, the better selenium conducts electricity. This property has made selenium useful in devices that respond to the intensity of light, such as electric eyes, photo cells, light meters for cameras and copiers. Selenium can also produce electricity directly from sunlight and is used in solar cells. Selenium is also a semiconductor and is used in some types of solid-state electronics as well as in rectifiers, devices which convert alternating current electricity into direct current electricity. In addition to its use in electrical devices, selenium is also used to make a ruby-red color in glasses and enamels, as a photographic toner and as an additive to stainless steel.
Selenium forms few inorganic compounds, none of which are commercially important. They include selenious acid (H2SeO3), selenium dichloride (SeCl2) and selenium oxychloride (SeOCl2).
Selenium is used in Xerography for reproducing and copying documents, letters, etc. It is used by the glass industry to decolorize glass and to make ruby-colored glasses and enamels. It is also used as a photographic toner, and as an additive to stainless steel.
Isotopes in Earth/Planetary Science
Molecules, atoms, and ions of the stable isotopes of selenium possess slightly different physical and chemical properties, and they commonly will be fractionated during physical, chemical, and biological processes, giving rise to variations in isotopic abundances and in atomic weights. There are measureable variations in the isotopic abundances of selenium in natural terrestrial materials (Fig. IUPAC.34.1).
Isotopes in Industry
75Se (with a half-life of 120 days) is used for X-ray radiography of welds to visualize welds and ensure that each weld is appropriate for its purpose [274] P. Hayward, D. Currie. “Radiography of welds using seleniuim 75, Ir 192 and x-rays”, in Asia-Pacific Conference on NDT, Auckland, New Zealand (2006)..
Isotopes in Medicine
75Se-selenomethionine (organic compound that combines to form proteins, found in Brazil nuts and soybeans) has been used to study the production of digestive enzymes (biological catalysts that accelerates chemical reactions) [275] A. C. Colella, F. Pigorini. Br. J. Radiol.40, 662 (1967).. Selenium stable isotopes are used in metabolic studies to monitor selenium intake and output [276] C. A. Swanson, D. C. Reamer, C. Veillon, J. C. King, O. A. Levander. Am. J. Clin. Nutr.38, 169 (1983)., [277] Public Health Service Agency for Toxic Substances and Disease Registry. Toxicological Profile for Selenium, U.S. Department of Health and Human Services (2014), Feb. 26; http://www.atsdr.cdc.gov/ToxProfiles/tp92.pdf..
Isotopes Used as a Source of Radioactive Isotope(s)
77Se and 78Se are used to produce the therapeutic radioisotope 77Br via the 77Se (n, p) 77Br and the 78Se (n, 2p) 77Br reactions, respectively. 80Se is used to produce 80mBr via the reaction 80Se (n, p) 80mBr. The m the superscript of 80mBr indicates a metastable state of the isotope.
Selenium occurs in oxidation states from −2 to +6, with −2, +4, and +6 especially important. Hydrogen selenide, H₂Se, is a highly toxic gas and the selenium analogue of hydrogen sulfide. Selenium dioxide, SeO₂, is a useful oxidizing reagent and forms selenous acid, H₂SeO₃, in water. Selenates such as sodium selenate, Na₂SeO₄, resemble sulfates chemically but are biologically more active. Metal selenides are important semiconductors, including cadmium selenide, CdSe, and copper indium gallium selenide used in thin-film photovoltaics.
See more information at the Selenium compound page.
Selenium is essential in trace amounts, but excess intake can cause selenosis, with gastrointestinal effects, hair and nail changes, and a garlic-like breath odor from volatile metabolites. Elemental selenium is less acutely hazardous than many soluble selenite and selenate salts, but dust exposure should be controlled. Hydrogen selenide, H₂Se, is extremely poisonous, and industrial selenium fumes or aerosols require strict ventilation and monitoring.
Hydrogen selenide at a concentration of 1.5 ppm is intolerable to man. Selenium occurs in some solid in amounts sufficient to produce serious effects on animals feeding on plants, such as locoweed, grown in such soils. Exposure to selenium compounds (as Se) in air should not exceed 0.2 mg/m3 (8-hour time-weighted average - 40-hour week).
Selenium is widely dispersed in sulfide ores, sedimentary rocks, soils, and waters, usually at low concentrations. Weathering and irrigation can mobilize selenate and selenite, which are taken up by plants and can bioaccumulate in food webs. Some plants tolerate and concentrate selenium, while many others show toxicity only where soils or drainage waters are selenium-rich. Microorganisms can reduce soluble selenium species to less mobile elemental selenium or volatile methylated forms.
Selenium is not normally mined as a primary product. Most commercial supply is recovered as a by-product from anode slimes produced during electrolytic refining of copper, with smaller links to other nonferrous metal processing. Demand is spread across glass manufacture, metallurgy, chemicals, electronics, and thin-film photovoltaic materials, so supply depends strongly on copper refining rather than direct selenium ore availability. Substitution has reduced some older electrical uses, but recovery remains economically useful because selenium is concentrated in refinery residues. Recycling occurs mainly through industrial scrap and process residues rather than consumer products.
Obtained from lead, copper and nickel refining. Conducts electricity when struck by light.
Selenium is a relatively uncommon cosmic element compared with lighter chalcogens. Its stable isotopes are produced mainly by neutron-capture processes in evolved stars and supernova-related environments, with contributions from both slow and rapid neutron capture. In planetary materials it behaves partly as a chalcophile element, tending to associate with sulfides rather than silicate minerals.
- Gray selenium conducts electricity better when illuminated.
- Selenium can replace sulfur in some amino acids, forming selenocysteine and selenomethionine.
- The smell associated with selenium exposure often comes from volatile methylated selenium compounds.
- Selenium was identified in residues from sulfuric acid manufacture.
- Some selenium-rich plants can poison grazing animals on naturally seleniferous soils.
- Cadmium selenide quantum dots can emit size-tunable visible light.
Görseller
Özellikler
Fiziksel
- Atom yarıçapı (ampirik)
- 115 pm Tüm elementlerin Atom yarıçapı (ampirik) değerlerini karşılaştır →
- Kovalent yarıçap
- 120 pm Tüm elementlerin Kovalent yarıçap değerlerini karşılaştır →
- Van der Waals yarıçapı
- 190 pm Tüm elementlerin Van der Waals yarıçapı değerlerini karşılaştır →
- Metalik yarıçap
- 117 pm Tüm elementlerin Metalik yarıçap değerlerini karşılaştır →
- Yoğunluk
- 4809 kg/m³ Tüm elementlerin Yoğunluk değerlerini karşılaştır →
- Molar hacim
- 0,0165 L/mol
- STP'deki faz
- Katı Tüm elementlerin STP'deki faz değerlerini karşılaştır →
- Erime noktası
- 220,5 °C Tüm elementlerin Erime noktası değerlerini karşılaştır →
- Kaynama noktası
- 684,85 °C Tüm elementlerin Kaynama noktası değerlerini karşılaştır →
- Isıl iletkenlik
- 0,52 W/(m·K) Tüm elementlerin Isıl iletkenlik değerlerini karşılaştır →
- Özgül ısı kapasitesi
- 0,321 J/(g·K) Tüm elementlerin Özgül ısı kapasitesi değerlerini karşılaştır →
- Molar ısı kapasitesi
- 25,363 J/(mol·K) Tüm elementlerin Molar ısı kapasitesi değerlerini karşılaştır →
- Kristal yapı
- Hekzagonal sıkı paket Tüm elementlerin Kristal yapı değerlerini karşılaştır →
Kimyasal
- Elektronegatiflik (Pauling)
- 2,55 Tüm elementlerin Elektronegatiflik (Pauling) değerlerini karşılaştır →
- Elektronegatiflik (Allen)
- 2,424
- Elektron ilgisi
- 2,0206 eV
- İyonlaşma enerjisi (1.)
- 9,752368 eV Tüm elementlerin İyonlaşma enerjisi (1.) değerlerini karşılaştır →
- İyonlaşma enerjisi (2.)
- 21,196073 eV Tüm elementlerin İyonlaşma enerjisi (2.) değerlerini karşılaştır →
- İyonlaşma enerjisi (3.)
- 31,697109 eV Tüm elementlerin İyonlaşma enerjisi (3.) değerlerini karşılaştır →
- İyonlaşma enerjisi (4.)
- 42,947148 eV Tüm elementlerin İyonlaşma enerjisi (4.) değerlerini karşılaştır →
- İyonlaşma enerjisi (5.)
- 68,300235 eV Tüm elementlerin İyonlaşma enerjisi (5.) değerlerini karşılaştır →
- Yükseltgenme basamakları
- −2, −1, 0, +1, +2, +3, +4, +5, +6 Tüm elementlerin Yükseltgenme basamakları değerlerini karşılaştır →
- Değerlik elektronları
- 6 Tüm elementlerin Değerlik elektronları değerlerini karşılaştır →
- Allotroplar
- ["gray", "vitreous"]
- Elektron dizilimi
- [Ar] 4s2 3d10 4p4
Termodinamik
- Kritik nokta (sıcaklık)
- 1493 °C
- Erime ısısı
- 0,0693372 eV Tüm elementlerin Erime ısısı değerlerini karşılaştır →
- Buharlaşma ısısı
- 0,27258123 eV Tüm elementlerin Buharlaşma ısısı değerlerini karşılaştır →
- Süblimleşme ısısı
- 2,352697 eV
- Atomlaşma ısısı
- 2,352697 eV
- Atomlaşma entalpisi
- 2,35477 eV
Nükleer
- Protonlar
- 34 Tüm elementlerin Protonlar değerlerini karşılaştır →
- Nötronlar
- 46 Tüm elementlerin Nötronlar değerlerini karşılaştır →
- Bilinen izotoplar
- 33 Tüm elementlerin Bilinen izotoplar değerlerini karşılaştır →
- Kararlı izotoplar
- 4 Tüm elementlerin Kararlı izotoplar değerlerini karşılaştır →
- En kararlı izotop
- Se-80
- Keşif yılı
- 1817
Bolluk
- Bolluk (yer kabuğu)
- 0,05 mg/kg Tüm elementlerin Bolluk (yer kabuğu) değerlerini karşılaştır →
- Bolluk (okyanus)
- 2 × 10−4 mg/L Tüm elementlerin Bolluk (okyanus) değerlerini karşılaştır →
Kristal Yapı
- Örgü sabiti a
- 436 pm
Elektronik Yapı
- Kabuk başına elektron sayısı
- 2, 8, 18, 6 Tüm elementlerin Kabuk başına elektron sayısı değerlerini karşılaştır →
Tanımlayıcılar
- CAS numarası
- 7782-49-2 Tüm elementlerin CAS numarası değerlerini karşılaştır →
- Terim simgesi
- 3P2
- InChI
- InChI=1S/Se
- InChI Anahtarı
- BUGBHKTXTAQXES-UHFFFAOYSA-N
Elektron Dizilimi Ölçülmüş
Se: 3d¹⁰ 4s² 4p⁴[Ar] 3d¹⁰ 4s² 4p⁴1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁴Atom modeli
İzotoplar nötron sayısını, kütleyi ve kararlılığı değiştirir; nötr bir atomun elektron dizilimini değiştirmez.
Şematik atom modeli, ölçekli değildir.
Atomik Parmak İzi
Emisyon / Soğurma Spektrumu
İzotop Dağılımı
| Kütle numarası | Atom kütlesi (u) | Doğal bolluk | Yarı ömür |
|---|---|---|---|
| 76 Kararlı | 75,919213704 ± 0,000000017 | 9,3700% | Kararlı |
| 77 Kararlı | 76,919914154 ± 0,000000067 | 7,6300% | Kararlı |
| 78 Kararlı | 77,91730928 ± 0,0000002 | 23,7700% | Kararlı |
| 80 Kararlı | 79,9165218 ± 0,0000013 | 49,6100% | Kararlı |
Faz / Hâl
Neden: erime noktasının (220,5 °C) 195,5 °C altında
Şematik, ölçekli değil
Faz geçiş noktaları
Geçiş enerjileri
Erime noktasında 1 mol maddeyi eritmek için gereken enerji
Kaynama noktasında 1 mol maddeyi buharlaştırmak için gereken enerji
Süblimleşme noktasında 1 mol maddeyi süblimleştirmek için gereken enerji
Yoğunluk
Standart koşullarda
Standart koşullarda
İleri düzey
Atomik Spektrumlar
34 kayıttan 10 tanesi gösteriliyor. İyon yüküne göre sıralandı (artan).
Spektral Çizgi Kayıtları ?
| İyon | Yük | Toplam çizgi sayısı | Geçiş olasılıkları | Düzey gösterimleri |
|---|---|---|---|---|
| Se I | 0 | 138 | 0 | 0 |
| Se II | +1 | 39 | 0 | 0 |
| Se III | +2 | 39 | 0 | 0 |
| Se IV | +3 | 22 | 0 | 0 |
| Se V | +4 | 17 | 0 | 0 |
Enerji Düzeyi Kayıtları ?
| İyon | Yük | Düzeyler |
|---|---|---|
| Se I | 0 | 173 |
| Se II | +1 | 78 |
| Se III | +2 | 53 |
| Se IV | +3 | 29 |
| Se V | +4 | 15 |
| Se VI | +5 | 7 |
| Se VII | +6 | 45 |
| Se VIII | +7 | 37 |
| Se IX | +8 | 2 |
| Se X | +9 | 2 |
İyon Yarıçapları
| Yük | Koordinasyon | Spin | Yarıçap |
|---|---|---|---|
| -2 | 6 | Mevcut değil | 198 pm |
| +4 | 6 | Mevcut değil | 50 pm |
| +6 | 4 | Mevcut değil | 28.000000000000004 pm |
| +6 | 6 | Mevcut değil | 42 pm |
Bileşikler
İzotoplar (4)
Naturally selenium contains six stable isotopes. Fifteen other isotopes have been characterized. The element is a member of the sulfur family and resembles sulfur both in its various forms and in its compounds.
| Kütle numarası | Atom kütlesi (u) | Doğal bolluk | Yarı ömür | Bozunma türü | |
|---|---|---|---|---|---|
| 76 Kararlı | 75,919213704 ± 0,000000017 | 9,3700% ± 0,2900% | Kararlı | stable | |
| 77 Kararlı | 76,919914154 ± 0,000000067 | 7,6300% ± 0,1600% | Kararlı | stable | |
| 78 Kararlı | 77,91730928 ± 0,0000002 | 23,7700% ± 0,2800% | Kararlı | stable | |
| 80 Kararlı | 79,9165218 ± 0,0000013 | 49,6100% ± 0,4100% | Kararlı | stable |
Genişletilmiş Özellikler
Kovalent Yarıçaplar (Genişletilmiş)
- Kovalent yarıçap (Pyykkö)
- 116 pm
- Kovalent yarıçap (Pyykkö, çift bağ)
- 107 pm
- Kovalent yarıçap (Pyykkö, üçlü bağ)
- 107 pm
- Kovalent yarıçap (Bragg)
- 117 pm
Van der Waals Yarıçapları
- Bondi
- 190 pm
- Batsanov
- 190 pm
- Alvarez
- 182 pm
- UFF
- 420,5 pm
- MM3
- 229 pm
- Dreiding
- 403 pm
Atom ve Metalik Yarıçaplar
- Atom yarıçapı (Rahm)
- 224 pm
- Metalik yarıçap (C12)
- 140 pm
Numaralandırma Ölçekleri
- Mendeleev
- 101
- Pettifor
- 93
- Glawe
- 95
Elektronegatiflik Ölçekleri
- Ghosh
- 0
- Gunnarsson–Lundqvist
- 6
- Robles–Bartolotti
- 5
Kutuplanabilirlik ve Dispersiyon
- Dipol kutuplanabilirliği
- 28,9 a.u.
- Dipol kutuplanabilirliği (belirsizlik)
- 1 a.u.
- C₆
- 210 Ha·Bohr6
- C₆ (Gould–Bučko)
- 233 Ha·Bohr6
Tedarik Riski ve Ekonomi
- Üretim yoğunlaşması
- 35
- Göreli tedarik riski
- 7
- Rezerv dağılımı
- 22
- Siyasi istikrar (en büyük üretici)
- 77
- Siyasi istikrar (en büyük rezerv sahibi)
- 18
Faz Geçişleri ve Allotroplar
| Geçiş sıcaklığı | 453,15 K |
| Kaynama noktası | 958,15 K |
| Kritik nokta (sıcaklık) | 1766,15 K |
| Erime noktası | 493,95 K |
| Kaynama noktası | 958,15 K |
| Kritik nokta (sıcaklık) | 1766,15 K |
| Kritik nokta (basınç) | 27,2 MPa |
Yükseltgenme Basamağı Kategorileri
İleri Düzey Referans Verileri
Perdeleme Sabitleri (8)
| n | Orbital | σ |
|---|---|---|
| 1 | s | 0,7378 |
| 2 | p | 3,9348 |
| 2 | s | 9,1116 |
| 3 | d | 15,523 |
| 3 | p | 15,295 |
| 3 | s | 14,5966 |
| 4 | p | 25,7128 |
| 4 | s | 24,2424 |
Kristal Yarıçaplarının Ayrıntıları (4)
| Yük | CN | Spin | rcrystal (pm) | Köken |
|---|---|---|---|---|
| -2 | VI | 184 | Pauling's (1960) crystal radius, | |
| 4 | VI | 64 | Ahrens (1952) ionic radius, | |
| 6 | IV | 42 | ||
| 6 | VI | 56 | calculated, |
İzotop Bozunma Türleri (52)
| İzotop | Mod | Şiddet |
|---|---|---|
| 63 | B+ | 100% |
| 63 | B+p | 89% |
| 63 | 2p | 0,5% |
| 64 | B+ | — |
| 64 | B+p | — |
| 65 | B+ | 100% |
| 65 | B+p | 87% |
| 66 | B+ | 100% |
| 66 | B+p | — |
| 67 | B+ | 100% |
X Işını Saçılma Faktörleri (506)
| Enerji (eV) | f₁ | f₂ |
|---|---|---|
| 10 | — | 5,20241 |
| 10,1617 | — | 5,36005 |
| 10,3261 | — | 5,52247 |
| 10,4931 | — | 5,63017 |
| 10,6628 | — | 5,66221 |
| 10,8353 | — | 5,69443 |
| 11,0106 | — | 5,71762 |
| 11,1886 | — | 5,72709 |
| 11,3696 | — | 5,73659 |
| 11,5535 | — | 5,7461 |
Ek Veriler
Estimated Crustal Abundance
The estimated element abundance in the earth's crust.
5×10-2 milligrams per kilogram
Kaynaklar (1)
- [5] Selenium https://education.jlab.org/itselemental/ele034.html
Estimated Oceanic Abundance
The estimated element abundance in the earth's oceans.
2×10-4 milligrams per liter
Kaynaklar (1)
- [5] Selenium https://education.jlab.org/itselemental/ele034.html
Production
Production of this element (from raw materials or other compounds containing the element).
Selenium is found in a few rare minerals such as crooksite and clausthalite. In years past it has been obtained from flue dusts remaining from processing copper sulfide ores, but the anode metal from electrolytic copper refineries now provide the source of most of the world's selenium. Selenium is recovered by roasting the mud with soda or sulfuric acid, or by smelting them with soda and niter.
Kaynaklar (1)
- [6] Selenium https://periodic.lanl.gov/34.shtml
Kaynaklar
(9)
Data deposited in or computed by PubChem
The half-life and atomic mass data was provided by the Atomic Mass Data Center at the International Atomic Energy Agency.
Element data are cited from the Atomic weights of the elements (an IUPAC Technical Report). The IUPAC periodic table of elements can be found at https://iupac.org/what-we-do/periodic-table-of-elements/. Additional information can be found within IUPAC publication doi:10.1515/pac-2015-0703 Copyright © 2020 International Union of Pure and Applied Chemistry.
The information are cited from Pure Appl. Chem. 2018; 90(12): 1833-2092, https://doi.org/10.1515/pac-2015-0703.
Thomas Jefferson National Accelerator Facility (Jefferson Lab) is one of 17 national laboratories funded by the U.S. Department of Energy. The lab's primary mission is to conduct basic research of the atom's nucleus using the lab's unique particle accelerator, known as the Continuous Electron Beam Accelerator Facility (CEBAF). For more information visit https://www.jlab.org/
The periodic table at the LANL (Los Alamos National Laboratory) contains basic element information together with the history, source, properties, use, handling and more. The provenance data may be found from the link under the source name.
The periodic table contains NIST's critically-evaluated data on atomic properties of the elements. The provenance data that include data for atomic spectroscopy, X-ray and gamma ray, radiation dosimetry, nuclear physics, and condensed matter physics may be found from the link under the source name. Ref: https://www.nist.gov/pml/atomic-spectra-database
This section provides all form of data related to element Selenium.
The element property data was retrieved from publications.