Selenium (Se)

chemical element with symbol Se and atomic number 34

Atomic Number	34
Atomic Weight	78.971
mass number	80

Group	16
Period	4
Block	p

proton	34 p⁺
neutron	46 n⁰
electron	34 e^-

Āhuatanga Ōkiko

Atomic Radius	115 pm 224 pm
molar volume	16.5 cm³/mol
covalent radius	116 pm 107 pm 107 pm 117 pm 120 pm
Metallic Radius	117 pm 140 pm
ionic radius	198 pm 50 pm 28 pm 42 pm
Crystal Radius	184 pm 64 pm 42 pm 56 pm
Van der Waals radius	190 pm 190 pm 403 pm 190 pm 229 pm 420.5 pm
density	4.809 g/cm³ 3,990 kg/m³

Chemical Property

energy

proton affinity
electron affinity	2.02067 eV/particle
ionization energy	9.752392 eV/particle 21.196 eV/particle 31.697 eV/particle 42.947 eV/particle 68.3 eV/particle 81.827 eV/particle 155.33 eV/particle 184 eV/particle 219 eV/particle 255 eV/particle 291 eV/particle 342.9 eV/particle 383 eV/particle 426 eV/particle 473 eV/particle 517 eV/particle 650.5 eV/particle 693.38 eV/particle 739.8 eV/particle 798 eV/particle 845.8 eV/particle 887 eV/particle 989.6 eV/particle 1,036.362 eV/particle 2,540.7 eV/particle 2,674 eV/particle 2,820 eV/particle 2,964 eV/particle 3,146 eV/particle 3,301.8 eV/particle 3,507 eV/particle 3,636.526 eV/particle 15,367.4907 eV/particle 15,968.083 eV/particle

enthalpy of vaporization	59.7 kJ/mol
enthalpy of fusion	5.23 kJ/mol
standard enthalpy of formation	227.2 kJ/mol
electron

electron shell	2, 8, 18, 6

valence electron	6 ⓘ

electron configuration	[Ar] 3d¹⁰ 4s² 4p⁴ⓘ 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁴

oxidation number	-2, -1, 0, 1, 2, 3, 4, 5, 6
electronegativity	14.34 eV/particle 0.2240328 2.55
Electrophilicity Index	2.2408492709619536 eV/particle
fundamental state of matter

phase of matter	Solid
gaseous state of matter
Boiling Point	958.15 K 958.15 K
Melting Point	453.15 K 493.95 K
critical pressure	27.2 MPa
critical temperature	1,766.15 K 1,766.15 K
triple point
appearance
color	Gray #ff1493 #ffa100 #ffa100
appearance	black, red, and gray (not pictured) allotropes
refractive index	1.000895
thermodynamic material property
Thermal Conductivity	0.52 W/(m K)
thermal expansion
molar heat capacity	25.363 J/(mol K)
Specific Heat Capacity	0.321 J/(g⋅K)
heat capacity ratio
electrical properties
type
electrical conductivity
electrical resistivity
superconductivity
magnetism
type	diamagnetic
magnetic susceptibility (Mass)	-0.000000004 m³/Kg
magnetic susceptibility (Molar)	-0.000000000316 m³/mol
magnetic susceptibility (Volume)	-0.0000193
magnetic ordering
Curie temperature
Néel temperature
structure
Crystal Structure	Simple Monoclinic (HEX)
lattice constant	4.36 Å
Lattice Angles	π/2, 1.58493, π/2
mechanical property
hardness	736 MPa 2 MPa
bulk modulus	8.3 GPa
shear modulus	3.7 GPa
Young's modulus	10 GPa
Poisson's ratio	0.33
speed of sound	3,350 m/s
classification
Category	Other nonmetals, Nonmetals
CAS Group	VIB
IUPAC Group	VIA
Glawe Number	95
Mendeleev Number	101
Pettifor Number	93
Geochemical Class	semi-volatile
Goldschmidt classification	chalcophile

other

Gas Basicity
polarizability	28.9 ± 1 a₀
C6 Dispersion Coefficient	210 a₀ 233 a₀
allotrope	Amorphous Red Selenium, Amorphous Black Selenium, Monoclinic Selenium, Hexagonal Selenium
Neutron cross section	11.7
Neutron Mass Absorption	0.0056
quantum number	3P2
space group	14 (P121/c1)

Isotopes of Selenium

Stable Isotopes	3
Unstable Isotopes	30
Natural Isotopes	6

⁶³Se

mass number	63
neutron number	29
Relative Atomic Mass	62.981911 ± 0.000537 Da
g-factor
natural abundance
radioactivity	☢️ radioactive element
half-life	13.2 ± 3.9 ms
spin	3/2
nuclear quadrupole moment
time of discovery or invention	2016
parity	-

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

⁶⁴Se

mass number	64
neutron number	30
Relative Atomic Mass	63.971165 ± 0.000537 Da
g-factor	0
natural abundance
radioactivity	☢️ radioactive element
half-life	22.6 ± 0.2 ms
spin	0
nuclear quadrupole moment	0
time of discovery or invention	2005
parity	+

decay mode	intensity
β⁺ (β⁺ decay; β⁺ = ϵ + e⁺)
β⁺ p (β⁺-delayed proton emission)

⁶⁵Se

mass number	65
neutron number	31
Relative Atomic Mass	64.964552 ± 0.000322 Da
g-factor
natural abundance
radioactivity	☢️ radioactive element
half-life	34.2 ± 0.7 ms
spin	3/2
nuclear quadrupole moment
time of discovery or invention	1993
parity	-

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

⁶⁶Se

mass number	66
neutron number	32
Relative Atomic Mass	65.955276 ± 0.000215 Da
g-factor	0
natural abundance
radioactivity	☢️ radioactive element
half-life	54 ± 4 ms
spin	0
nuclear quadrupole moment	0
time of discovery or invention	1993
parity	+

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

⁶⁷Se

mass number	67
neutron number	33
Relative Atomic Mass	66.949994 ± 0.000072 Da
g-factor
natural abundance
radioactivity	☢️ radioactive element
half-life	133 ± 4 ms
spin	5/2
nuclear quadrupole moment
time of discovery or invention	1991
parity	-

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

⁶⁸Se

mass number	68
neutron number	34
Relative Atomic Mass	67.941825236 ± 0.000000532 Da
g-factor	0
natural abundance
radioactivity	☢️ radioactive element
half-life	35.5 ± 0.7 s
spin	0
nuclear quadrupole moment	0
time of discovery or invention	1990
parity	+

decay mode	intensity
β⁺ (β⁺ decay; β⁺ = ϵ + e⁺)	100%

⁶⁹Se

mass number	69
neutron number	35
Relative Atomic Mass	68.939414845 ± 0.000001599 Da
g-factor
natural abundance
radioactivity	☢️ radioactive element
half-life	27.4 ± 0.2 s
spin	1/2
nuclear quadrupole moment	0
time of discovery or invention	1974
parity	-

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

⁷⁰Se

mass number	70
neutron number	36
Relative Atomic Mass	69.933515521 ± 0.0000017 Da
g-factor	0
natural abundance
radioactivity	☢️ radioactive element
half-life	41.1 ± 0.3 m
spin	0
nuclear quadrupole moment	0
time of discovery or invention	1950
parity	+

decay mode	intensity
β⁺ (β⁺ decay; β⁺ = ϵ + e⁺)	100%

⁷¹Se

mass number	71
neutron number	37
Relative Atomic Mass	70.932209431 ± 0.000003 Da
g-factor
natural abundance
radioactivity	☢️ radioactive element
half-life	4.74 ± 0.05 m
spin	5/2
nuclear quadrupole moment
time of discovery or invention	1957
parity	-

decay mode	intensity
β⁺ (β⁺ decay; β⁺ = ϵ + e⁺)	100%

⁷²Se

mass number	72
neutron number	38
Relative Atomic Mass	71.927140506 ± 0.0000021 Da
g-factor	0
natural abundance
radioactivity	☢️ radioactive element
half-life	8.4 ± 0.08 d
spin	0
nuclear quadrupole moment	0
time of discovery or invention	1948
parity	+

decay mode	intensity
ϵ (electron capture)	100%

⁷³Se

mass number	73
neutron number	39
Relative Atomic Mass	72.926754881 ± 0.000007969 Da
g-factor	0.19822222222222 ± 0.0028888888888889
natural abundance
radioactivity	☢️ radioactive element
half-life	7.15 ± 0.09 h
spin	9/2
nuclear quadrupole moment
time of discovery or invention	1948
parity	+

decay mode	intensity
β⁺ (β⁺ decay; β⁺ = ϵ + e⁺)	100%

⁷⁴Se

mass number	74
neutron number	40
Relative Atomic Mass	73.922475933 ± 0.000000015 Da
g-factor	0
natural abundance	0.86 ± 0.03
radioactivity	☢️ radioactive element
half-life
spin	0
nuclear quadrupole moment	0
time of discovery or invention	1922
parity	+

decay mode	intensity
2β⁺ (double β⁺ decay)

⁷⁵Se

mass number	75
neutron number	41
Relative Atomic Mass	74.92252287 ± 0.000000078 Da
g-factor	0.2732 ± 0.004
natural abundance
radioactivity	☢️ radioactive element
half-life	119.78 ± 0.03 d
spin	5/2
nuclear quadrupole moment	1.1 ± 0.2
time of discovery or invention	1947
parity	+

decay mode	intensity
ϵ (electron capture)	100%

⁷⁶Se

mass number	76
neutron number	42
Relative Atomic Mass	75.919213702 ± 0.000000017 Da
g-factor	0
natural abundance	9.23 ± 0.07
radioactivity	stable isotope
half-life	Not Radioactive ☢️
spin	0
nuclear quadrupole moment	0
time of discovery or invention	1922
parity	+

⁷⁷Se

mass number	77
neutron number	43
Relative Atomic Mass	76.91991415 ± 0.000000067 Da
g-factor	1.06712 ± 0.0001
natural abundance	7.6 ± 0.07
radioactivity	stable isotope
half-life	Not Radioactive ☢️
spin	1/2
nuclear quadrupole moment	0
time of discovery or invention	1922
parity	-

⁷⁸Se

mass number	78
neutron number	44
Relative Atomic Mass	77.917309244 ± 0.000000191 Da
g-factor	0
natural abundance	23.69 ± 0.22
radioactivity	stable isotope
half-life	Not Radioactive ☢️
spin	0
nuclear quadrupole moment	0
time of discovery or invention	1922
parity	+

⁷⁹Se

mass number	79
neutron number	45
Relative Atomic Mass	78.918499252 ± 0.000000238 Da
g-factor	-0.29085714285714 ± 0.0042857142857143
natural abundance
radioactivity	☢️ radioactive element
half-life	327 ± 28 ky
spin	7/2
nuclear quadrupole moment	0.8 ± 0.2
time of discovery or invention	1950
parity	+

decay mode	intensity
β⁻ (β⁻ decay)	100%

⁸⁰Se

mass number	80
neutron number	46
Relative Atomic Mass	79.916521761 ± 0.000001016 Da
g-factor	0
natural abundance	49.8 ± 0.36
radioactivity	☢️ radioactive element
half-life
spin	0
nuclear quadrupole moment	0
time of discovery or invention	1922
parity	+

decay mode	intensity
2β⁻ (double β⁻ decay)

⁸¹Se

mass number	81
neutron number	47
Relative Atomic Mass	80.917993019 ± 0.000001049 Da
g-factor
natural abundance
radioactivity	☢️ radioactive element
half-life	18.45 ± 0.12 m
spin	1/2
nuclear quadrupole moment	0
time of discovery or invention	1948
parity	-

decay mode	intensity
β⁻ (β⁻ decay)	100%

⁸²Se

mass number	82
neutron number	48
Relative Atomic Mass	81.916699531 ± 0.0000005 Da
g-factor	0
natural abundance	8.82 ± 0.15
radioactivity	☢️ radioactive element
half-life	87.6 ± 1.5 Ey
spin	0
nuclear quadrupole moment	0
time of discovery or invention	1922
parity	+

decay mode	intensity
2β⁻ (double β⁻ decay)	100%

⁸³Se

mass number	83
neutron number	49
Relative Atomic Mass	82.919118604 ± 0.000003259 Da
g-factor
natural abundance
radioactivity	☢️ radioactive element
half-life	22.25 ± 0.04 m
spin	9/2
nuclear quadrupole moment
time of discovery or invention	1937
parity	+

decay mode	intensity
β⁻ (β⁻ decay)	100%

⁸⁴Se

mass number	84
neutron number	50
Relative Atomic Mass	83.918466761 ± 0.000002105 Da
g-factor	0
natural abundance
radioactivity	☢️ radioactive element
half-life	3.26 ± 0.1 m
spin	0
nuclear quadrupole moment	0
time of discovery or invention	1960
parity	+

decay mode	intensity
β⁻ (β⁻ decay)	100%

⁸⁵Se

mass number	85
neutron number	51
Relative Atomic Mass	84.922260758 ± 0.000002804 Da
g-factor
natural abundance
radioactivity	☢️ radioactive element
half-life	32.9 ± 0.3 s
spin	5/2
nuclear quadrupole moment
time of discovery or invention	1960
parity

decay mode	intensity
β⁻ (β⁻ decay)	100%

⁸⁶Se

mass number	86
neutron number	52
Relative Atomic Mass	85.924311732 ± 0.000002705 Da
g-factor	0
natural abundance
radioactivity	☢️ radioactive element
half-life	14.3 ± 0.3 s
spin	0
nuclear quadrupole moment	0
time of discovery or invention	1973
parity	+

decay mode	intensity
β⁻ (β⁻ decay)	100%
β⁻ n (β⁻-delayed neutron emission)

⁸⁷Se

mass number	87
neutron number	53
Relative Atomic Mass	86.928688616 ± 0.000002405 Da
g-factor
natural abundance
radioactivity	☢️ radioactive element
half-life	5.5 ± 0.06 s
spin	3/2
nuclear quadrupole moment
time of discovery or invention	1968
parity	+

decay mode	intensity
β⁻ (β⁻ decay)	100%
β⁻ n (β⁻-delayed neutron emission)	0.6%

⁸⁸Se

mass number	88
neutron number	54
Relative Atomic Mass	87.93141749 ± 0.000003604 Da
g-factor	0
natural abundance
radioactivity	☢️ radioactive element
half-life	1.53 ± 0.06 s
spin	0
nuclear quadrupole moment	0
time of discovery or invention	1970
parity	+

decay mode	intensity
β⁻ (β⁻ decay)	100%
β⁻ n (β⁻-delayed neutron emission)	0.99%

⁸⁹Se

mass number	89
neutron number	55
Relative Atomic Mass	88.936669058 ± 0.000004003 Da
g-factor
natural abundance
radioactivity	☢️ radioactive element
half-life	430 ± 50 ms
spin	5/2
nuclear quadrupole moment
time of discovery or invention	1971
parity	+

decay mode	intensity
β⁻ (β⁻ decay)	100%
β⁻ n (β⁻-delayed neutron emission)	7.8%

⁹⁰Se

mass number	90
neutron number	56
Relative Atomic Mass	89.940096 ± 0.000354 Da
g-factor	0
natural abundance
radioactivity	☢️ radioactive element
half-life	210 ± 80 ms
spin	0
nuclear quadrupole moment	0
time of discovery or invention	1994
parity	+

decay mode	intensity
β⁻ (β⁻ decay)	100%
β⁻ n (β⁻-delayed neutron emission)

⁹¹Se

mass number	91
neutron number	57
Relative Atomic Mass	90.9457 ± 0.000465 Da
g-factor
natural abundance
radioactivity	☢️ radioactive element
half-life	270 ± 50 ms
spin	1/2
nuclear quadrupole moment	0
time of discovery or invention	1975
parity	+

decay mode	intensity
β⁻ (β⁻ decay)	100%
β⁻ n (β⁻-delayed neutron emission)	21%
2n (2-neutron emission)

⁹²Se

mass number	92
neutron number	58
Relative Atomic Mass	91.94984 ± 0.000429 Da
g-factor	0
natural abundance
radioactivity	☢️ radioactive element
half-life
spin	0
nuclear quadrupole moment	0
time of discovery or invention	1997
parity	+

decay mode	intensity
β⁻ (β⁻ decay)
β⁻ n (β⁻-delayed neutron emission)
2n (2-neutron emission)

⁹³Se

mass number	93
neutron number	59
Relative Atomic Mass	92.956135 ± 0.000429 Da
g-factor
natural abundance
radioactivity	☢️ radioactive element
half-life
spin	1/2
nuclear quadrupole moment	0
time of discovery or invention	1997
parity	+

decay mode	intensity
β⁻ (β⁻ decay)
β⁻ n (β⁻-delayed neutron emission)
2n (2-neutron emission)

⁹⁴Se

mass number	94
neutron number	60
Relative Atomic Mass	93.96049 ± 0.000537 Da
g-factor	0
natural abundance
radioactivity	☢️ radioactive element
half-life
spin	0
nuclear quadrupole moment	0
time of discovery or invention	1997
parity	+

decay mode	intensity
β⁻ (β⁻ decay)
β⁻ n (β⁻-delayed neutron emission)
2n (2-neutron emission)

⁹⁵Se

mass number	95
neutron number	61
Relative Atomic Mass	94.9673 ± 0.000537 Da
g-factor
natural abundance
radioactivity	☢️ radioactive element
half-life
spin	3/2
nuclear quadrupole moment
time of discovery or invention	2010
parity	+

decay mode	intensity
β⁻ (β⁻ decay)
β⁻ n (β⁻-delayed neutron emission)
2n (2-neutron emission)

kōrero nehe

discoverer or inventor	Jöns Berzelius
location of discovery	Sweden
time of discovery or invention	1818
etymology	Greek: selênê (moon).
pronunciation	si-LEE-ni-em (Ingarihi)

source

Abundance
Abundance in Earth's crust	0.05 mg/kg
natural abundance (Moana nui)	0.0002 mg/L
natural abundance (human body)	0.000005 %
natural abundance (meteoroid)	0.0013 %
natural abundance (Te Rā)
Abundance in Universe	0.000003 %

Nuclear Screening Constants

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

Selenium on ChemicalAid

selenium

Art & Architecture Thesaurus ID	300156319
Australian Educational Vocabulary ID	scot/3574
BNCF Thesaurus ID	52421
Biblioteca Nacional de España ID	XX534324
Bibliothèque nationale de France ID	121383271
Brockhaus Enzyklopädie online ID	selen
CAS Registry Number	7782-49-2
ChEBI ID	27568
ChemSpider ID	4885617
DSSTOX compound identifier	DTXCID701261
DSSTox substance ID	DTXSID9021261
Den Store Danske ID	selen
DrugBank ID	11135
ECHA Substance Infocard ID	100.029.052
Encyclopædia Britannica Online ID	science/selenium
Encyclopædia Universalis ID	selenium
Freebase ID	/m/025sf8g
French Vikidia ID	Sélénium
GND ID	4180872-1
Gran Enciclopèdia Catalana ID	0238414
Great Russian Encyclopedia Online ID	3546300
HCIS ID	4102
HSDB ID	4493
Human Metabolome Database ID	HMDB0001349
ICSC ID	0072
InChI	InChI=1S/Se
InChIKey	BUGBHKTXTAQXES-UHFFFAOYSA-N
KBpedia ID	Selenium
KEGG ID	C01529
Library of Congress authority ID	sh85119688
MeSH descriptor ID	D012643
NALT ID	33437
NCI Drug Dictionary ID	selenium
NDF-RT ID	N0000148196
NDL Authority ID	00570819
NKCR AUT ID	ph127055
National Library of Israel J9U ID	987007529471405171
OmegaWiki Defined Meaning	3373
OpenAlex ID	C553756173
PSH ID	5808
PatientsLikeMe treatment ID	selenium
Probes And Drugs ID	PD056990
PubChem CID	6326970
Quora topic ID	Selenium-2
Quora topic ID	Selenium-element
RxNorm ID	9641
Store medisinske leksikon ID	selen
Store norske leksikon ID	selen
Treccani ID	selenio
UK Archival Thesaurus ID	f2/mt225/4347/9119
UMLS CUI	C0036581
UNII	H6241UJ22B
USGS Thesaurus ID	1572
WikiSkripta ID	12122
Wolfram Language entity code	Entity["Mineral", "Selenium"]
WordNet 3.1 Synset ID	14678354-n
YSO ID	10413
ZVG number	7340

Selenium (Se)

Āhuatanga Ōkiko

Chemical Property

other

Isotopes of Selenium

63Se

64Se

65Se

66Se

67Se

68Se

69Se

70Se

71Se

72Se

73Se

74Se

75Se

76Se

77Se

78Se

79Se

80Se

81Se

82Se

83Se

84Se

85Se

86Se

87Se

88Se

89Se

90Se

91Se

92Se

93Se

94Se

95Se

kōrero nehe

source

Nuclear Screening Constants

⁶³Se

⁶⁴Se

⁶⁵Se

⁶⁶Se

⁶⁷Se

⁶⁸Se

⁶⁹Se

⁷⁰Se

⁷¹Se

⁷²Se

⁷³Se

⁷⁴Se

⁷⁵Se

⁷⁶Se

⁷⁷Se

⁷⁸Se

⁷⁹Se

⁸⁰Se

⁸¹Se

⁸²Se

⁸³Se

⁸⁴Se

⁸⁵Se

⁸⁶Se

⁸⁷Se

⁸⁸Se

⁸⁹Se

⁹⁰Se

⁹¹Se

⁹²Se

⁹³Se

⁹⁴Se

⁹⁵Se