Selenium Elemental Symbol

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Sélénium Selen Selenio Selênio Selenio Selen

Selenide(Se) atomic and molecular weight, atomic number and elemental symbolSelenium is a Block P, Group 16, Period 4 element. Elemental SeleniumThe number of electrons in each of Selenium's shells is 2, 8, 18, 6 and its electron configuration is [Ar] 3d10 4s2 4p4. The selenium atom has a radius of and its Van der Waals radius is In its elemental form selenium's CAS number is 7782-49-2. Selenium Bohr Model Selenium was discovered and first isolated by Jöns Jakob Berzelius and Johann Gottlieb Gahn in 1817. It is produced from selenide which is found in many sulfide ores. The origin of the name Selenium comes from the Greek word "Selênê" meaning moon.

Selenium exhibits both photovoltaic action, where light is converted directly into electricity, and photoconductive action, where the electrical resistance decreases with increased illumination. Below its melting point, selenium is a p-type semiconductor and has many uses in electronic and solid-state applications. Selenium is available as metal and compounds with purities from 99% to 99.999% (ACS grade to ultra-high purity). High Purity (99.999%) Selenium (Se) Sputtering TargetElemental or metallic forms include pellets, rod, wire and granules for evaporation source material purposes. Selenium nanoparticles and nanopowders provide ultra-high surface area which nanotechnology research and recent experiments demonstrate function to create new and unique properties and benefits. Oxides are available in powder and dense pellet form for such uses as optical coating and thin film applications. Oxides tend to be insoluble. Fluorides are another insoluble form for uses in which oxygen is undesirable such as metallurgy, chemical and physical vapor deposition and in some optical coatings. Selenium is also available in soluble forms including chlorides, nitrates and acetates. These compounds can be manufactured as solutions at specified stoichiometries.

The EPA does not classify selenium as carcinogenic, although selenium sulfide is a probable carcinogen. Selenates and selenites which are compounds of selenium, are highly toxic. Hydrogen selenide gas (SeH2) is the most acutely toxic compound of selenium. Safety data for Selenium and its compounds can vary widely depending on the form. For potential hazard information, toxicity, and road, sea and air transportation limitations, such as DOT Hazard Class, DOT Number, EU Number, NFPA Health rating and RTECS Class, please see the specific material or compound referenced in the Products tab below.

  • Properties
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  • Isotopes
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Selenium Properties

Symbol: Se Melting Point: 220.8 oC, 429.44 oF, 493.95 K
Atomic Number: 34 Boiling Point: 685 oC, 1265 oF, 958.15 K
Atomic Weight: 78.96 Density: 4808 kg m-3
Element Category: nonmetal Liquid Density @ Melting Point: 3.99 g·cm−3
Group, Period, Block: 16 (chalcogens), 4, p Specific Heat: 0.767 Cal/g/K @ 25 °C
    Heat of Vaporization 90 kJ mol-1
CHEMICAL STRUCTURE Heat of Fusion 5.1 kJ mol-1
Electrons: 34 Thermal Conductivity: 0.00519 W/cm/K @ 298.2 K
Protons: 34 Thermal Expansion: (25 °C) (amorphous) 37 µm·m−1·K−1
Neutrons: 45 Electrical Resistivity: 106 microhm-cm @ 0°C
Electron Configuration: [Ar]4s23d104p4  Electronegativity: 2.4 Paulings
Atomic Radius: 120 pm Tensile Strength: N/A
Covalent Radius: 120±4 pm Molar Heat Capacity: 25.363 J·mol−1·K−1
Van der Waals radius: 190 pm Young's Modulus: 10 GPa
Oxidation States: 6, 4, -2 Shear Modulus: 3.7 GPa
Phase: Solid Bulk Modulus: 8.3 GPa
Crystal Structure: hexagonal Poisson Ratio: 0.33
Magnetic Ordering: diamagnetic Mohs Hardness: 2.0
1st Ionization Energy: 940.97 kJ mol-1 Vickers Hardness: N/A
2nd Ionization Energy: 2044.54 kJ mol-1 Brinell Hardness: 736 MPa
3rd Ionization Energy: 2973.74 kJ mol-1 Speed of Sound: (20 °C) 3350 m·s−1
CAS Number: 7782-49-2 Abundance in typical human body, by weight: N/A
ChemSpider ID: 4885617 Abundance in typical human body, by atom: N/A
PubChem CID: 6326970 Abundance in universe, by weight: 0.1 ppb
MDL Number: MFCD00134090 Abundance in universe, by atom: 0.001 ppb
EC Number: 231-957-4 Discovered By: Jöns Jakob Berzelius and Johann Gottlieb Gahn
Beilstein Number: N/A Discovery Date: 1817
SMILES Identifier: [Se]  
InChI Identifier: InChI=1S/Se Other Names: Selen, Selenio

Selenium Products

Metal Forms  •  Compounds  •  Alloys  •  Oxide Forms
Sputtering Targets  •  Nanomaterials  •  Semiconductor Materials •  Isotopes

Metal Forms

Selenium Balls
Selenium Bands
Selenium Bits
Selenium Board
Selenium Briquette
Selenium Capsules
Selenium Chunk
Selenium Circle
Selenium Coil
Selenium Concentrate
Selenium Cylinder
Selenium Disc
Selenium Dust
Selenium Flake
Selenium Flanges
Selenium Foil
Selenium Fragments
Selenium Grain
Selenium Granules
Selenium Ingot
Selenium Lump
Selenium Mesh
Selenium Metal
Selenium Microfoil
Selenium Microleaf
Selenium Nugget
Selenium Parts
Selenium Pieces
Selenium Pebbles
Selenium Pellets
Selenium Pills
Selenium Plate
Selenium Powder
Selenium Precipitate
Selenium Prisms
Selenium Puck
Selenium Residue
Selenium Ribbon
Selenium Rings
Selenium Rocks
Selenium Rod
Selenium Samples
Selenium Scraps
Selenium Segments
Selenium Shaving
Selenium Sheet
Selenium Shot
Selenium Sleeves
Selenium Slugs
Selenium Specimens
Selenium Spheres
Selenium Spring
Selenium Strip
Selenium Tape
Selenium Tube
Selenium Wafer
Selenium Wire


Barium Selenate
Barium Selenite
Beryllium Selenate
Cadmium Selenate
Cadmium Selenite
Calcium Selenate
Calcium Selenite
Cerium Selenate
Cesium Selenate
Cobalt Selenate
Cobalt Selenite
Copper Selenate
Copper Selenite
Copper(II) Selenite Dihydrate
Gold Selenate
Lead Selenate
Lead Selenite
Lithium Selenate
Lithium Selenite
Magnesium Selenate
Magnesium Selenite
Manganese Selenate
Manganese Selenite
Nickel Selenate
Nickel Selenite
Phenylselenyl Bromide
Potassium Selenate
Potassium Selenite
Selenium Acid
Selenium(I) Bromide SeBr
Selenium Monobromide Se2Br2
Selenium(IV) Bromide SeBr4
Selenium Bromide, Polymer-bound
Selenium Carbide
Selenium(I) Chloride Se2Cl2
Selenium(IV) Chloride SeCl4
Selenium Chloride Solution
Selenium Fluoride
Selenium Oxide
Silver Selenate
Silver Selenite
Sodium Selenate
Sodium Selenate, Anhydrous
Sodium Selenite
Strontium Selenate
Thallium Selenate
Tin Selenite
Zinc Selenite
Sputtering Targets

Aluminum Selenide Sputtering Target
Antimony Selenide Sputtering Target
Arsenic Selenide Sputtering Target
Bismuth Selenide Sputtering Target
Cadmium Selenide Sputtering Target
Calcium Selenide Sputtering Target
Cerium Selenide Sputtering Target
Cesium Selenide Sputtering Target
Chromium Selenide Sputtering Target
Cobalt Selenide Sputtering Target
Copper Gallium Selenide Sputtering Target
CIGS Sputtering Target
CIGSS Sputtering Target
Copper Indium Selenide Sputtering Target
Copper Selenide Sputtering Target
Dysprosium Selenide Sputtering Target
Erbium Selenide Sputtering Target
Europium Selenide Sputtering Target
Gadolinium Selenide Sputtering Target
Gallium(II) Selenide Sputtering Target
Gallium(III) Selenide Sputtering Target
Germanium Selenide Sputtering Target
Gold Selenide Sputtering Target
Hafnium Selenide Sputtering Target
Holmium Selenide Sputtering Target
Indium Selenide Sputtering Target
Indium(II) Selenide Sputtering Target
Iron Selenide Sputtering Target
Lanthanum Selenium Sputtering Target
Lead Selenide Sputtering Target
Lithium Selenide Sputtering Target
Lutetium Selenide Sputtering Target
Magnesium Selenium Sputtering Target
Manganese Selenide Sputtering Target
Molybdenum Selenide Sputtering Target
Neodymium Selenide Sputtering Target
Nickel Selenide Sputtering Target
Niobium Selenide Sputtering Target
Osmium Selenide Sputtering Target
Palladium Selenide Sputtering Target
Platinum Selenide Sputtering Target
Praseodymium Selenide Sputtering Target
Rhenium Selenide Sputtering Target
Rhodium Selenide Sputtering Target
Ruthenium Selenide Sputtering Target
Samarium Selenium Sputtering Target
Scandium Selenide Sputtering Target
Selenium Oxide Rotatable Sputtering Target
Selenium Oxide Sputtering Target
Selenium Phosphide Sputtering Target
Selenium Rotatable Sputtering Target
Selenium Sputtering Target
Selenium Telluride Sputtering Target
Silicon Selenide Sputtering Target
Silver Selenide Sputtering Target
Strontium Selenide Sputtering Target
Tantalum Selenide Sputtering Target
Terbium Selenide Sputtering Target
Thallium Selenide Sputtering Target
Thorium Selenide Sputtering Target
Thulium Selenide Sputtering Target
Tin Selenide Sputtering Target
Titanium Selenide Sputtering Target
Tungsten Selenide Sputtering Target
Vanadium Selenide Sputtering Target
Ytterbium Selenide Sputtering Target
Yttrium Selenide Sputtering Target
Zinc Selenide Sputtering Target
Zirconium Selenide Sputtering Target

Organometallic Compounds

Diethyl Selenide


Cadmium Selenide Hollow Nanospheres
Cadmium Selenide Nanotubes
Cadmium Selenide Quantum Dots
CdSe/ZnS Quantum Dots
Copper Indium Gallium Selenide Nanoparticles
Copper Indium Selenide Nanoparticles
Mn doped ZnO Quantum Dots
Mn/ZnSe Quantum Dots
PbSe Quantum Dots
Selenium Nanofoil
Selenium Nanoparticles
Selenium Nanoprisms
Selenium Oxide Nanopowder
ZnCdSe/ZnS Quantum Dots


Selenium 74 Metal Isotope
Selenium 76 Metal Isotope
Selenium 77 Metal Isotope
Selenium 82 Metal Isotope


Lead Selenium Granule
Crystal/ Semiconductor Materials

Aluminum Selenide
Antimony Selenide
Arsenic Selenide
Barium Selenide
Bismuth Selenide
Bismuth Selenide Single Crystal
Bismuth Telluride/Antimony Selenide Solid Solution
Cadmium Selenide
Cadmium Selenide Hollow Spheres
Cadmium Selenide Tube
Calcium Selenide
Cerium Selenide
Cesium Selenide
Chromium Selenide
CIGS Granule
CIGS Powder
CIGS Single Crystal
CIGSS Granule
CIGSS Powder
Cobalt Selenide
Copper Indium Selenide Powder
Copper Indium Selenide Particles
Copper Indium Selenide Single Crystal
Copper Selenide
Disilver Selenide
Dysprosium Selenide
Erbium Selenide
Europium Selenide
Gadolinium Selenide
Gallium(II) Selenide
Gallium Selenide Crystal
Germanium(II) Selenide
Gold Selenide
Digold Triselenide
Hafnium Selenide
Holmium Selenide
Indium Selenide Crystal
Indium(III) Selenide In2Se3
Indium(II) Selenide InSe
Iridium Selenide
Iron Selenide
Lead Selenide
PbTe/SbSe Solid Solution
PbTe/SnTe/PbSe Solid Solution
Lanthanum Selenide
Lithium Selenide
Lutetium Selenide
Magnesium Selenide
Manganese Selenide
Mercury Indium Selenium Granule
Mercury Indium Selenium Powder
Mercury Indium Selenium Lump
Mercury Selenide
Molybdenum Selenide MoSe
Molybdenum Selenide(II) MoSe2
Neodymium Selenide
Nickel Selenide
Niobium Selenide
Osmium Selenide
Palladium Selenide
Platinum Selenide
Praseodymium Selenide
Rhenium Selenide
Rhodium Selenide
Ruthenium Selenide
Samarium Selenide
Scandium Selenide
Selenium Phosphide
Selenium Sulfide
Silicon Selenide
Single Crystal Iron Selenide Telluride
Selenium Telluride
Silver Selenide
Strontium Selenide
Tantalum Selenide
Terbium Selenide
Thallium Selenide
Thorium Selenide
Thulium Selenide
Tin(II) Selenide SnSe
Tin(IV) Selenide SnSe2
Titanium Selenide
Tungsten Selenide
Vanadium Selenide
Ytterbium Selenide
Yttrium Selenide
Zinc Selenide
Zinc Selenide Beam Splitters
Zinc Selenide Windows
Zinc Selenide Lenses
Zinc Selenide Prisms
Zinc Selenide Pieces
Zirconium Selenide

Oxide Forms

Selenium Oxide Nanopowder
Selenium Oxide Pellets
Selenium Oxide Pieces
Selenium Oxide Powder
Selenium Oxide Rotatable Sputtering Target
Selenium Oxide Shot
Selenium Oxide Sputtering Target
Selenium Oxide Tablets

Recent Research & Development for Selenium

  • Understanding the paradox of selenium contamination in mercury mining areas: High soil content and low accumulation in rice. Zhang H, Feng X, Jiang C, Li Q, Liu Y, Gu C, Shang L, Li P, Lin Y, Larssen T. Environ Pollut. 2014.
  • Transport of selenium oxyanions through TiO2porous media: Column experiments and multi-scale modeling. Nsir K, Svecova L, Sardin M, Simonnot MO. J Contam Hydrol. 2014.
  • Distribution and speciation of ambient selenium in contrasted soils, from mineral to organic rich. Tolu J, Thiry Y, Bueno M, Jolivet C, Potin-Gautier M, Le Hécho I. Sci Total Environ. 2014.
  • Proteomics of Desulfovibrio desulfuricans and X-ray absorption spectroscopy to investigate mercury methylation in the presence of selenium. Truong HY, Chen YW, Saleh M, Nehzati S, George GN, Pickering IJ, Belzile N. Metallomics. 2014
  • Ovarian and uterine characteristics and onset of puberty in adolescent offspring: Effects of maternal diet and selenium supplementation in sheep. Grazul-Bilska AT, Neville TL, Borowczyk E, Sharma A, Reynolds LP, Caton JS, Redmer DA, Vonnahme KA. Theriogenology. 2014.
  • Effects of organic selenium on lead-induced impairments of spatial learning and memory as well as synaptic structural plasticity in rats. Han XJ, Xiao YM, Ai BM, Hu XX, Wei Q, Hu QS. Biol Pharm Bull. 2014
  • Comparison of rapidly synergistic cloud point extraction and ultrasound-assisted cloud point extraction for trace selenium coupled with spectrophotometric determination. Wen X, Zhang Y, Li C, Fang X, Zhang X. Spectrochim Acta A Mol Biomol Spectrosc. 2014.
  • Large-scale speciation of selenium in rice proteins using ICP-MS assisted electrospray MS/MS proteomics. Cheajesadagul P, Bianga J, Arnaudguilhem C, Lobinski R, Szpunar J. Metallomics. 2014
  • Mercury and selenium in the muscle of piscivorous common mergansers (Mergus merganser) from a selenium-deficient European country. Kalisinska E, Gorecki J, Okonska A, Pilarczyk B, Tomza-Marciniak A, Budis H, Lanocha N, Kosik-Bogacka DI, Kavetska KM, Macherzynski M, Golas JM. Ecotoxicol Environ Saf. 2014
  • Cobalt selenium oxohalides: catalysts for water oxidation. Rabbani F, Svengren H, Zimmermann I, Hu S, Laine T, Hao W, Akermark B, Akermark T, Johnsson M. Dalton Trans. 2014
  • Dynamic Selenium Assimilation, Distribution, Efflux, and Maternal Transfer in Japanese Medaka Fed a Diet of Se-enriched Mayflies. Conley JM, Watson AT, Xie L, Buchwalter DB. Environ Sci Technol. 2014
  • Nephroprotective potential of selenium and taurine against mercuric chloride induced nephropathy in rats. Agha FE, Youness ER, Selim MM, Ahmed HH. Ren Fail. 2014.
  • Effects of selenium supplementation on plasma progesterone concentrations in pregnant heifers. Kamada H, Nonaka I, Takenouchi N, Amari M. Anim Sci J. 2014
  • Inverse mercury and selenium concentration patterns between herbivorous and piscivorous fish in the Tapajos River, Brazilian Amazon. Sampaio da Silva D, Lucotte M, Paquet S, Brux G, Lemire M. Ecotoxicol Environ Saf.
  • Effects of dietary selenium deficiency or excess on gene expression of selenoprotein N in chicken muscle tissues. Zhang JL, Zhang ZW, Shan AS, Xu SW. Biol Trace Elem Res. 2014
  • Method validation for simultaneous determination of chromium, molybdenum and selenium in infant formulas by ICP-OES and ICP-MS. Khan N, Jeong IS, Hwang IM, Kim JS, Choi SH, Nho EY, Choi JY, Kwak BM, Ahn JH, Yoon T, Kim KS. Food Chem.
  • Biogenic Synthesis of Selenium Nanoparticles and Their Effect on As(III)-Induced Toxicity on Human Lymphocytes. Prasad KS, Selvaraj K. Biol Trace Elem Res. 2014
  • Selenium:Mercury Molar Ratios in Bullfrog and Leopard Frog Tadpoles from the Northeastern United States. Burger J, Feinberg J, Jeitner C, Gochfeld M, Donio M, Pittfield T. Ecohealth. 2014
  • Antioxidant activities of Se-SPI produced from soybean as accumulation and biotransformation reactor of natural selenium. Hu J, Zhao Q, Cheng X, Selomulya C, Bai C, Zhu X, Li X, Xiong H. Food Chem. 2014 Mar.
  • Cadmium induced hepatotoxicity in chickens (Gallus domesticus) and ameliorative effect by selenium. Li JL, Jiang CY, Li S, Xu SW. Ecotoxicol Environ Saf.

Selenium Isotopes

Selenium (Se) has six naturally occurring isotopes. Five of these are stable: 74Se, 76Se, 77Se, 78Se, and 80Se.

Nuclide Symbol Isotopic Mass Half-Life Nuclear Spin
74Se 73.9224764 Observationally Stable 0+
76Se 75.9192136 Stable 0+
77Se 76.9199140 Stable 1/2-
78Se 77.9173091 Stable 0+
80Se 9.9165213 Observationally Stable 0+