Selenium

Selenium (Se)

Selenium is the 34th element in the periodic table and has a symbol of Se and atomic number of 34. It has an atomic weight of 78.971 and a mass number of 80. Selenium has thirty-four protons and forty-six neutrons in its nucleus, and thirty-four electrons in four shells. It is located in group sixteen, period four and block p of the periodic table. Metalloid element, belongs to group 16 of the periodic table. Multiple allotropic forms exist. Chemically resembles sulphur. Discovered in 1817 by Jons J. Berzelius.
Atomic Number34
Atomic Weight78.971
Mass Number80
Group16
Period4
Blockp
Protons34 p+
Neutrons46 n0
Electrons34 e-
Animated Bohr Model of Se (Selenium)

Physical Properties

Atomic Radius
Molar Volume
Covalent Radius
Metallic Radius
Ionic Radius
Crystal Radius
Van der Waals Radius
Density
Atomic Radii of the Elements: Selenium0102030405060708090100110120130140150160170180190pmAtomic RadiusCovalent RadiusMetallic RadiusVan der Waals Radius

Chemical Properties

Energy
Proton Affinity
Electron Affinity
Ionization Energy
Ionization Energies of Se (Selenium)
Heat of Vaporization
Heat of Fusion
Heat of Formation
Electrons
Electron Shells2, 8, 18, 6
Bohr Model: Se (Selenium)
Valence Electrons6
Lewis Structure: Se (Selenium)
Electron Configuration[Ar] 3d10 4s2 4p4
1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p4
Enhanced Bohr Model of Se (Selenium)
Orbital Diagram of Se (Selenium)
Oxidation States-2, -1, 0, 1, 2, 3, 4, 5, 6
Electronegativity
2.55
Electrophilicity Index
States of Matter
PhaseSolid
Gas Phase
Boiling Point
Melting Point
Critical Pressure
Critical Temperature
Triple Point
Visual

Selenium is a Gray. Se has a CPK of #ff1493, Jmol of #ffa100, and MOLCAS GV of #ffa100. The Appearance of Element 34 is black, red, and gray (not pictured) allotropes. The Refractive Index of Selenium (Se) is 1.000895.

Color
Gray
Appearanceblack, red, and gray (not pictured) allotropes
Refractive Index
1.000895
Thermodynamic Properties
Thermal Conductivity
Thermal Expansion
Molar Heat Capacity
Specific Heat Capacity
Heat Capacity Ratio (Adiabatic Index)
Electrical Properties
Type
Electrical Conductivity
Electrical Resistivity
Superconducting Point
Magnetism
Typediamagnetic
Magnetic Susceptibility (Mass)
-0.000000004 m³/Kg
Magnetic Susceptibility (Molar)
-0.000000000316 m³/mol
Magnetic Susceptibility (Volume)
-0.0000193
Magnetic Ordering
Curie Point
Neel Point
Structure

The Crystal Structure of Selenium is HEX. The lattice constant of Se is 4.36 Å. The lattice angles of Element 34 are π/2, 1.58493, π/2.

Crystal StructureSimple Monoclinic (HEX)
Lattice Constant
Lattice Anglesπ/2, 1.58493, π/2
Mechanical Properties

Selenium has a Brinell of 736 MPa, and Mohs hardness of 2 MPa. The Bulk Modulus of Se is 8.3 GPa. The Shear Modulus of Element 34 is 3.7 GPa. The Young Modulus of Selenium (Se) is 10 GPa. The Poisson Ratio of Selenium is 0.33. The Speed of Sound of Se is 3350 m/s.

Hardness
Bulk Modulus
Shear Modulus
Young's Modulus
Poisson Ratio
0.33
Speed of Sound
Classification

The CAS Group of Selenium is VIB. The IUPAC Group of Se is VIA. The Glawe Number of Element 34 is 95. The Mendeleev Number of Selenium (Se) is 101. The Pettifor Number of Selenium is 93. The Geochemical Class of Se is semi-volatile. The Goldschmidt Class of Element 34 is chalcophile.

CategoryOther nonmetals, Nonmetals
CAS GroupVIB
IUPAC GroupVIA
Glawe Number95
Mendeleev Number101
Pettifor Number93
Geochemical Classsemi-volatile
Goldschmidt Classchalcophile

Other

The Dipole Polarizability of Selenium is 28.9 plus or minus 1 a₀. Se has a C6 Dispersion Coefficient (CD) of 210 a₀, and C6 Dispersion Coefficient (GB) of 233 a₀. The Allotropes of Element 34 are Amorphous Red Selenium, Amorphous Black Selenium, Monoclinic Selenium, Hexagonal Selenium. The Neutron Cross Section of Selenium (Se) is 11.7. The Neutron Mass Absorption of Selenium is 0.0056. The Quantum Numbers of Se is 3P2. The Space Group of Element 34 is 14 (P121/c1).

Gas Basicity
Dipole Polarizability
C6 Dispersion Coefficient
AllotropesAmorphous Red Selenium, Amorphous Black Selenium, Monoclinic Selenium, Hexagonal Selenium
Neutron Cross Section
11.7
Neutron Mass Absorption
0.0056
Quantum Numbers3P2
Space Group14 (P121/c1)

Isotopes of Selenium

Stable Isotopes3
Unstable Isotopes30
Natural Isotopes6
Isotopic Composition8049.80%8049.80%7823.69%7823.69%769.23%769.23%828.82%828.82%777.60%777.60%740.86%740.86%

63Se

Mass Number63
Neutron Number29
Relative Atomic Mass
G-Factor
Abundance
Radioactivity☢️ Radioactive
Half Life
13.2 ± 3.9 ms
Spin3/2
Quadrupole Moment
Discovery Year2016
Parity-

Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)100%
β+ p (β+-delayed proton emission)89%
2p (2-proton emission)0.5%

64Se

Mass Number64
Neutron Number30
Relative Atomic Mass
G-Factor
0
Abundance
Radioactivity☢️ Radioactive
Half Life
22.6 ± 0.2 ms
Spin0
Quadrupole Moment
0
Discovery Year2005
Parity+

Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)
β+ p (β+-delayed proton emission)

65Se

Mass Number65
Neutron Number31
Relative Atomic Mass
G-Factor
Abundance
Radioactivity☢️ Radioactive
Half Life
34.2 ± 0.7 ms
Spin3/2
Quadrupole Moment
Discovery Year1993
Parity-

Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)100%
β+ p (β+-delayed proton emission)87%

66Se

Mass Number66
Neutron Number32
Relative Atomic Mass
G-Factor
0
Abundance
Radioactivity☢️ Radioactive
Half Life
54 ± 4 ms
Spin0
Quadrupole Moment
0
Discovery Year1993
Parity+

Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)100%
β+ p (β+-delayed proton emission)

67Se

Mass Number67
Neutron Number33
Relative Atomic Mass
G-Factor
Abundance
Radioactivity☢️ Radioactive
Half Life
133 ± 4 ms
Spin5/2
Quadrupole Moment
Discovery Year1991
Parity-

Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)100%
β+ p (β+-delayed proton emission)0.5%

68Se

Mass Number68
Neutron Number34
Relative Atomic Mass
G-Factor
0
Abundance
Radioactivity☢️ Radioactive
Half Life
35.5 ± 0.7 s
Spin0
Quadrupole Moment
0
Discovery Year1990
Parity+

Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)100%

69Se

Mass Number69
Neutron Number35
Relative Atomic Mass
G-Factor
Abundance
Radioactivity☢️ Radioactive
Half Life
27.4 ± 0.2 s
Spin1/2
Quadrupole Moment
0
Discovery Year1974
Parity-

Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)100%
β+ p (β+-delayed proton emission)0.052%

70Se

Mass Number70
Neutron Number36
Relative Atomic Mass
G-Factor
0
Abundance
Radioactivity☢️ Radioactive
Half Life
41.1 ± 0.3 m
Spin0
Quadrupole Moment
0
Discovery Year1950
Parity+

Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)100%

71Se

Mass Number71
Neutron Number37
Relative Atomic Mass
G-Factor
Abundance
Radioactivity☢️ Radioactive
Half Life
4.74 ± 0.05 m
Spin5/2
Quadrupole Moment
Discovery Year1957
Parity-

Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)100%

72Se

Mass Number72
Neutron Number38
Relative Atomic Mass
G-Factor
0
Abundance
Radioactivity☢️ Radioactive
Half Life
8.4 ± 0.08 d
Spin0
Quadrupole Moment
0
Discovery Year1948
Parity+

Decay ModeIntensity
ϵ (electron capture)100%

73Se

Mass Number73
Neutron Number39
Relative Atomic Mass
G-Factor
0.19822222222222 ± 0.0028888888888889
Abundance
Radioactivity☢️ Radioactive
Half Life
7.15 ± 0.09 h
Spin9/2
Quadrupole Moment
Discovery Year1948
Parity+

Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)100%

74Se

Mass Number74
Neutron Number40
Relative Atomic Mass
G-Factor
0
Abundance
0.86 ± 0.03
Radioactivity☢️ Radioactive
Half Life
Spin0
Quadrupole Moment
0
Discovery Year1922
Parity+

Decay ModeIntensity
+ (double β+ decay)

75Se

Mass Number75
Neutron Number41
Relative Atomic Mass
G-Factor
0.2732 ± 0.004
Abundance
Radioactivity☢️ Radioactive
Half Life
119.78 ± 0.03 d
Spin5/2
Quadrupole Moment
1.1 ± 0.2
Discovery Year1947
Parity+

Decay ModeIntensity
ϵ (electron capture)100%

76Se

Mass Number76
Neutron Number42
Relative Atomic Mass
G-Factor
0
Abundance
9.23 ± 0.07
RadioactivityStable
Half LifeNot Radioactive ☢️
Spin0
Quadrupole Moment
0
Discovery Year1922
Parity+

77Se

Mass Number77
Neutron Number43
Relative Atomic Mass
G-Factor
1.06712 ± 0.0001
Abundance
7.6 ± 0.07
RadioactivityStable
Half LifeNot Radioactive ☢️
Spin1/2
Quadrupole Moment
0
Discovery Year1922
Parity-

78Se

Mass Number78
Neutron Number44
Relative Atomic Mass
G-Factor
0
Abundance
23.69 ± 0.22
RadioactivityStable
Half LifeNot Radioactive ☢️
Spin0
Quadrupole Moment
0
Discovery Year1922
Parity+

79Se

Mass Number79
Neutron Number45
Relative Atomic Mass
G-Factor
-0.29085714285714 ± 0.0042857142857143
Abundance
Radioactivity☢️ Radioactive
Half Life
327 ± 28 ky
Spin7/2
Quadrupole Moment
0.8 ± 0.2
Discovery Year1950
Parity+

Decay ModeIntensity
β (β decay)100%

80Se

Mass Number80
Neutron Number46
Relative Atomic Mass
G-Factor
0
Abundance
49.8 ± 0.36
Radioactivity☢️ Radioactive
Half Life
Spin0
Quadrupole Moment
0
Discovery Year1922
Parity+

Decay ModeIntensity
(double β decay)

81Se

Mass Number81
Neutron Number47
Relative Atomic Mass
G-Factor
Abundance
Radioactivity☢️ Radioactive
Half Life
18.45 ± 0.12 m
Spin1/2
Quadrupole Moment
0
Discovery Year1948
Parity-

Decay ModeIntensity
β (β decay)100%

82Se

Mass Number82
Neutron Number48
Relative Atomic Mass
G-Factor
0
Abundance
8.82 ± 0.15
Radioactivity☢️ Radioactive
Half Life
87.6 ± 1.5 Ey
Spin0
Quadrupole Moment
0
Discovery Year1922
Parity+

Decay ModeIntensity
(double β decay)100%

83Se

Mass Number83
Neutron Number49
Relative Atomic Mass
G-Factor
Abundance
Radioactivity☢️ Radioactive
Half Life
22.25 ± 0.04 m
Spin9/2
Quadrupole Moment
Discovery Year1937
Parity+

Decay ModeIntensity
β (β decay)100%

84Se

Mass Number84
Neutron Number50
Relative Atomic Mass
G-Factor
0
Abundance
Radioactivity☢️ Radioactive
Half Life
3.26 ± 0.1 m
Spin0
Quadrupole Moment
0
Discovery Year1960
Parity+

Decay ModeIntensity
β (β decay)100%

85Se

Mass Number85
Neutron Number51
Relative Atomic Mass
G-Factor
Abundance
Radioactivity☢️ Radioactive
Half Life
32.9 ± 0.3 s
Spin5/2
Quadrupole Moment
Discovery Year1960
Parity

Decay ModeIntensity
β (β decay)100%

86Se

Mass Number86
Neutron Number52
Relative Atomic Mass
G-Factor
0
Abundance
Radioactivity☢️ Radioactive
Half Life
14.3 ± 0.3 s
Spin0
Quadrupole Moment
0
Discovery Year1973
Parity+

Decay ModeIntensity
β (β decay)100%
β n (β-delayed neutron emission)

87Se

Mass Number87
Neutron Number53
Relative Atomic Mass
G-Factor
Abundance
Radioactivity☢️ Radioactive
Half Life
5.5 ± 0.06 s
Spin3/2
Quadrupole Moment
Discovery Year1968
Parity+

Decay ModeIntensity
β (β decay)100%
β n (β-delayed neutron emission)0.6%

88Se

Mass Number88
Neutron Number54
Relative Atomic Mass
G-Factor
0
Abundance
Radioactivity☢️ Radioactive
Half Life
1.53 ± 0.06 s
Spin0
Quadrupole Moment
0
Discovery Year1970
Parity+

Decay ModeIntensity
β (β decay)100%
β n (β-delayed neutron emission)0.99%

89Se

Mass Number89
Neutron Number55
Relative Atomic Mass
G-Factor
Abundance
Radioactivity☢️ Radioactive
Half Life
430 ± 50 ms
Spin5/2
Quadrupole Moment
Discovery Year1971
Parity+

Decay ModeIntensity
β (β decay)100%
β n (β-delayed neutron emission)7.8%

90Se

Mass Number90
Neutron Number56
Relative Atomic Mass
G-Factor
0
Abundance
Radioactivity☢️ Radioactive
Half Life
210 ± 80 ms
Spin0
Quadrupole Moment
0
Discovery Year1994
Parity+

Decay ModeIntensity
β (β decay)100%
β n (β-delayed neutron emission)

91Se

Mass Number91
Neutron Number57
Relative Atomic Mass
G-Factor
Abundance
Radioactivity☢️ Radioactive
Half Life
270 ± 50 ms
Spin1/2
Quadrupole Moment
0
Discovery Year1975
Parity+

Decay ModeIntensity
β (β decay)100%
β n (β-delayed neutron emission)21%
2n (2-neutron emission)

92Se

Mass Number92
Neutron Number58
Relative Atomic Mass
G-Factor
0
Abundance
Radioactivity☢️ Radioactive
Half Life
Spin0
Quadrupole Moment
0
Discovery Year1997
Parity+

Decay ModeIntensity
β (β decay)
β n (β-delayed neutron emission)
2n (2-neutron emission)

93Se

Mass Number93
Neutron Number59
Relative Atomic Mass
G-Factor
Abundance
Radioactivity☢️ Radioactive
Half Life
Spin1/2
Quadrupole Moment
0
Discovery Year1997
Parity+

Decay ModeIntensity
β (β decay)
β n (β-delayed neutron emission)
2n (2-neutron emission)

94Se

Mass Number94
Neutron Number60
Relative Atomic Mass
G-Factor
0
Abundance
Radioactivity☢️ Radioactive
Half Life
Spin0
Quadrupole Moment
0
Discovery Year1997
Parity+

Decay ModeIntensity
β (β decay)
β n (β-delayed neutron emission)
2n (2-neutron emission)

95Se

Mass Number95
Neutron Number61
Relative Atomic Mass
G-Factor
Abundance
Radioactivity☢️ Radioactive
Half Life
Spin3/2
Quadrupole Moment
Discovery Year2010
Parity+

Decay ModeIntensity
β (β decay)
β n (β-delayed neutron emission)
2n (2-neutron emission)
Selen 1

History

Selenium was first observed in about the year 1300 by the alchemist Arnold of Villanova. Selenium was discovered in 1817 by Jöns Jacob Berzelius and Johan Gottlieb Gahn who noted the similarity of the new element to the previously-known tellurium. In 1873, Willoughby Smith found that the electrical resistance of grey selenium was dependent on the ambient light. From the Greek word Selene, moon

DiscoverersJöns Berzelius
Discovery LocationSweden
Discovery Year1818
Etymology (Name Origin)Greek: selênê (moon).
Pronunciationsi-LEE-ni-em (English)
Many of selenium's compounds, such as selenates and selenites, are highly toxic
Selenium deficiency in animals can lead to slow growth

Uses

Selenium is used in the glass industry to decolorize glass and to make red-colored glasses and enamels. It is used as a catalyst in many chemical reactions. It is also used as a photographic toner, and as an additive to stainless steel. Selenium sulfide is used in anti-dandruff shampoos. Light causes it to conduct electricity more easily. It is used in photoelectric cells, TV cameras, xerography machines and as a semiconductor in solar batteries and rectifiers. Also colors glass red.

Sources

Obtained from lead, copper and nickel refining. Conducts electricity when struck by light.

Abundance
Abundance in Earth's crust
Natural Abundance (Oceans)
Natural Abundance (Human Body)
0.000005 %
Natural Abundance (Meteor)
0.0013 %
Natural Abundance (Sun)
Abundance in Universe
0.000003 %

Nuclear Screening Constants

1s0.7378
2p3.9348
2s9.1116
3d15.523
3p15.295
3s14.5966
4p25.7128
4s24.2424

Also Known As

  • Se
  • element 34
  • 34Se

Translations

  • Norwegian Bokmålselen
  • Frenchsélénium
  • Italianselenio
  • GermanSelen
  • Dutchseleen
  • Spanishselenio
  • Danishselen
  • Gujaratiસેલિનીયમ
  • Hungarianszelén
  • Afrikaansselenium
  • Amharicሴሊኒየም
  • AragoneseSelenio
  • Arabicسيلينيوم
  • AzerbaijaniSelen
  • Belarusianселен
  • Bulgarianселен
  • Banglaসেলেনিয়াম
  • BretonSeleniom
  • Bosnianselen
  • Catalanseleni
  • CorsicanSeleniu
  • Czechselen
  • ChuvashСелен
  • WelshSeleniwm
  • Divehiސެލެނިއަމް
  • Greekσελήνιο
  • Esperantoseleno
  • Estonianseleen
  • Basqueselenio
  • Persianسلنیم
  • Finnishseleeni
  • FaroeseSelen
  • FriulianSeleni
  • IrishSeiléiniam
  • Galicianselenio
  • ManxShellainium
  • Hakka Chineseselenium
  • Hebrewסלניום
  • Hindiसेलेनियम
  • Fiji HindiSelenium
  • CroatianSelenij
  • Haitian CreoleSelenyòm
  • Armenianսելեն
  • InterlinguaSelenium
  • Indonesianselenium
  • IdoSelenio
  • Icelandicselen
  • Japaneseセレン
  • Lojbanlurcmu
  • JavaneseSelenium
  • Georgianსელენიუმი
  • KazakhСелен
  • Kannadaಸೆಲೆನಿಯಮ್
  • Korean셀레늄
  • KomiСелен
  • Latinselenium
  • LuxembourgishSelen
  • LigurianSelenio
  • LithuanianSelenas
  • Latvianselēns
  • Macedonianселен
  • Malayalamസെലീനിയം
  • Marathiसेलेनियम
  • Western MariСелен
  • MalaySelenium
  • Burmeseဆီလီနီယမ်
  • Low GermanSelen
  • Norwegian Nynorskselen
  • OccitanSelèni
  • Punjabiਸਿਲੀਨੀਅਮ
  • Polishselen
  • Western Panjabiسلینیم
  • Portugueseselénio
  • QuechuaSilinyu
  • Romanianseleniu
  • Russianселен
  • Siciliansileniu
  • Serbo-CroatianSelen
  • SlovakSelén
  • SlovenianSelen
  • Serbianселен
  • Saterland FrisianSelen
  • Swedishselen
  • SwahiliSeleni
  • Tamilசெலீனியம்
  • Teluguసెలీనియం
  • Thaiซีลีเนียม
  • TurkishSelenyum
  • Uyghurسېلېن
  • Ukrainianселен
  • UzbekSelen
  • VepsSelen
  • Vietnameseselen
  • WaraySelenyo
  • KalmykСелен
  • Yiddishסעלעניום
  • YorubaSelenium
  • Chinese
  • English (Canada)Selenium
  • English (United Kingdom)selenium
  • German (Switzerland)Selen
  • Portuguese (Brazil)selênio
  • Cantonese
  • Central Kurdishسیلینیۆم
  • Northern FrisianSelen
  • CebuanoSelenio
  • TatarСелен
  • Odiaସେଲେନିଅମ
  • PiedmonteseSeleni
  • Newariसेलेनियम
  • ErzyaСелен
  • SomaliSeleniyaam
  • Belarusian (Taraskievica orthography)сэлен
  • Pashtoselenium
  • Literary Chinese
  • AlbanianSeleni
  • Chinese (Taiwan)
  • Chinese (Hong Kong SAR China)
  • Chinese (Traditional)
  • Chinese (Simplified)
  • Chinese (China)
  • AromanianSeleniu
  • KyrgyzСелен
  • cdoSă̤
  • Nepaliसेलेनियम
  • Sanskritसेलेनियम
  • Malteseselenju
  • LombardSelenio
  • Scottish GaelicSelenium
  • LimburgishSeleen
  • AsturianSeleniu
  • Paliसेलेनियम
  • TajikСелен
  • Gan Chinese
  • Mongolianселени
  • Min Nan ChineseSelenium
  • ExtremaduranSeleniu
  • Bhojpuriसेलीनियम
  • Tibetanསེ་ལེ་ནིམ།
  • SundaneseSélénium
  • Tagalogselenyo
  • Lingua Franca Novaselenio
  • kbpSɛlɩnɩyɔm
  • oloSelen
  • Wu Chinese
  • hywՍեղէն
  • SardinianSelèniu
  • Moroccan Arabicسيلينيوم
  • BashkirСелен
  • Egyptian Arabicسيلينيوم
  • BikolSelenyo
  • CornishSeleniom
  • BalineseSélénium
  • WalloonSeleniom
  • Skolt Samiseleeʹn
  • Northern Samiselena
  • Inari Samiseeleen
  • Urduسیلینیم