Arsenic (As)

Metalloid element of group 15. There are three allotropes, yellow, black, and grey. Reacts with halogens, concentrated oxidizing acids and hot alkalis. Albertus Magnus is believed to have been the first to isolate the element in 1250.

Atomic Number	33
Atomic Weight	74.921595
Mass Number	75

Group	15
Period	4
Block	p

Protons	33 p⁺
Neutrons	42 n⁰
Electrons	33 e^-

Properties

Energy
Atomic Radius	115 pm 231 pm
Molar Volume	13.1 cm³/mol
Covalent Radius	121 pm 114 pm 106 pm 126 pm 119 pm
Metallic Radius	121 pm 148 pm
Ionic Radius	58 pm 33.5 pm 46 pm
Crystal Radius	72 pm 47.5 pm 60 pm
Van der Waals Radius	205 pm 185 pm 415 pm 185 pm 236 pm 423 pm
Density	5.75 g/cm³ 5,220 kg/m³
Proton Affinity
Electron Affinity	0.804 eV/particle
Ionization Energy	9.789 eV/particle 18.5892 eV/particle 28.349 eV/particle 50.15 eV/particle 62.767 eV/particle 121.19 eV/particle 147 eV/particle 180 eV/particle 213 eV/particle 247 eV/particle 296 eV/particle 333 eV/particle 375 eV/particle 418 eV/particle 460 eV/particle 587.6 eV/particle 628.82 eV/particle 672.9 eV/particle 728.9 eV/particle 774 eV/particle 814 eV/particle 911.7 eV/particle 956.791 eV/particle 2,357 eV/particle 2,486 eV/particle 2,626 eV/particle 2,766 eV/particle 2,938 eV/particle 3,088.1 eV/particle 3,287 eV/particle 3,411.643 eV/particle 14,447.6778 eV/particle 15,028.906 eV/particle

Heat of Vaporization	32.4 kJ/mol
Heat of Fusion
Heat of Formation	302.5 kJ/mol
Electrons
Electron Shells	2, 8, 18, 5

Valence Electrons	5

Electron Configuration	[Ar] 3d¹⁰ 4s² 4p³

Oxidation States	-3, -2, -1, 0, 1, 2, 3, 4, 5
Electronegativity	13.08 eV/particle 0.2068208 2.18
Electrophilicity	1.5610969532554257 eV/particle
Phases
Phase	Solid
Gas Phase
Boiling Point	889.15 K
Melting Point	1,090.15 K
Critical Pressure	22.3 MPa
Critical Temperature	1,673.15 K
Triple Point	1,090.15 K 3,700 kPa
Visual
Color	Silver #ff1493 #bd80e3 #bd80e3
Appearance	metallic grey
Refractive Index	1.001552
Thermodynamic Properties
Thermal Conductivity
Thermal Expansion
Molar Heat Capacity	24.64 J/(mol K)
Specific Heat Capacity	0.329 J/(g⋅K)
Heat Capacity Ratio (Adiabatic Index)
Electrical Properties
Type	Conductor
Electrical Conductivity	3.3 MS/m
Electrical Resistivity	0.0000003 m Ω
Superconducting Point
Magnetism
Type	diamagnetic
Magnetic Susceptibility (Mass)	-0.0000000039 m³/Kg
Magnetic Susceptibility (Molar)	-0.000000000292 m³/mol
Magnetic Susceptibility (Volume)	-0.0000223
Magnetic Ordering
Curie Point
Neel Point
Structure
Crystal Structure	Simple Trigonal (RHL)
Lattice Constant	4.13 Å
Lattice Angles	π/2, π/2, 2 π/3
Mechanical Properties
Hardness	1,440 MPa 3.5 MPa
Bulk Modulus	22 GPa
Shear Modulus
Young Modulus	8 GPa
Poisson Ratio
Speed of Sound
Classification
Category	Metalloids, Metalloids
CAS Group	VB
IUPAC Group	VA
Glawe Number	90
Mendeleev Number	95
Pettifor Number	89
Geochemical Class	semi-volatile
Goldschmidt Class	chalcophile
Other
Gas Basicity
Dipole Polarizability	30 ± 1 a₀
C6 Dispersion Coefficient	246 a₀ 260 a₀
Allotropes	Yellow Arsenic, Black Arsenic, Gray Arsenic
Neutron Cross Section	4.2
Neutron Mass Absorption	0.002
Quantum Numbers	4S3/2
Space Group	166 (R_3m)

Isotopes of Arsenic

Stable Isotopes	1
Unstable Isotopes	32
Radioactive Isotopes	28

⁶⁰As

Abundance
Relative Atomic Mass	59.993945 ± 0.000429 Da
Mass Number	60
G-Factor
Half Life
Spin	5
Quadrupole Moment
Discovery Year
Parity	+

⁶⁰As Decay Modes

Decay Mode	Intensity
p (proton emission)	%

⁶¹As

Abundance
Relative Atomic Mass	60.981535 ± 0.000322 Da
Mass Number	61
G-Factor
Half Life
Spin	3/2
Quadrupole Moment
Discovery Year
Parity	-

⁶¹As Decay Modes

Decay Mode	Intensity
p (proton emission)	%

⁶²As

Abundance
Relative Atomic Mass	61.973784 ± 0.000322 Da
Mass Number	62
G-Factor
Half Life
Spin	1
Quadrupole Moment
Discovery Year
Parity	+

⁶²As Decay Modes

Decay Mode	Intensity
p (proton emission)	%

⁶³As

Abundance
Relative Atomic Mass	62.964036 ± 0.000215 Da
Mass Number	63
G-Factor
Half Life
Spin	3/2
Quadrupole Moment
Discovery Year
Parity	-

⁶³As Decay Modes

Decay Mode	Intensity
p (proton emission)	%

⁶⁴As

Abundance	Radioactive ☢️
Relative Atomic Mass	63.95756 ± 0.000218 Da
Mass Number	64
G-Factor	0
Half Life	69 ± 1.4 ms
Spin	0
Quadrupole Moment	0
Discovery Year	1995
Parity	+

⁶⁴As Decay Modes

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

⁶⁵As

Abundance	Radioactive ☢️
Relative Atomic Mass	64.949611 ± 0.000091 Da
Mass Number	65
G-Factor
Half Life	130.3 ± 0.6 ms
Spin	3/2
Quadrupole Moment
Discovery Year	1991
Parity	-

⁶⁵As Decay Modes

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

⁶⁶As

Abundance	Radioactive ☢️
Relative Atomic Mass	65.944148778 ± 0.0000061 Da
Mass Number	66
G-Factor	0
Half Life	95.77 ± 0.23 ms
Spin	0
Quadrupole Moment	0
Discovery Year	1978
Parity	+

⁶⁶As Decay Modes

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

⁶⁷As

Abundance	Radioactive ☢️
Relative Atomic Mass	66.93925111 ± 0.000000475 Da
Mass Number	67
G-Factor
Half Life	42.5 ± 1.2 s
Spin	5/2
Quadrupole Moment
Discovery Year	1980
Parity	-

⁶⁷As Decay Modes

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

⁶⁸As

Abundance	Radioactive ☢️
Relative Atomic Mass	67.936774127 ± 0.000001981 Da
Mass Number	68
G-Factor
Half Life	151.6 ± 0.8 s
Spin	3
Quadrupole Moment
Discovery Year	1971
Parity	+

⁶⁸As Decay Modes

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

⁶⁹As

Abundance	Radioactive ☢️
Relative Atomic Mass	68.932246289 ± 0.000034352 Da
Mass Number	69
G-Factor	0.6488 ± 0.0008
Half Life	15.2 ± 0.2 m
Spin	5/2
Quadrupole Moment
Discovery Year	1955
Parity	-

⁶⁹As Decay Modes

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

⁷⁰As

Abundance	Radioactive ☢️
Relative Atomic Mass	69.930934642 ± 0.0000015 Da
Mass Number	70
G-Factor	0.5276 ± 0.000125
Half Life	52.6 ± 0.3 m
Spin	4
Quadrupole Moment	0.09 ± 0.02
Discovery Year	1950
Parity	+

⁷⁰As Decay Modes

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

⁷¹As

Abundance	Radioactive ☢️
Relative Atomic Mass	70.927113594 ± 0.000004469 Da
Mass Number	71
G-Factor	0.6692 ± 0.0008
Half Life	65.3 ± 0.07 h
Spin	5/2
Quadrupole Moment	-0.021 ± 0.006
Discovery Year	1939
Parity	-

⁷¹As Decay Modes

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

⁷²As

Abundance	Radioactive ☢️
Relative Atomic Mass	71.926752291 ± 0.000004383 Da
Mass Number	72
G-Factor	-1.0805 ± 0.0003
Half Life	26 ± 0.1 h
Spin	2
Quadrupole Moment	-0.08 ± 0.02
Discovery Year	1939
Parity	-

⁷²As Decay Modes

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

⁷³As

Abundance	Radioactive ☢️
Relative Atomic Mass	72.923829086 ± 0.000004136 Da
Mass Number	73
G-Factor
Half Life	80.3 ± 0.06 d
Spin	3/2
Quadrupole Moment
Discovery Year	1948
Parity	-

⁷³As Decay Modes

Decay Mode	Intensity
ϵ (electron capture)	100%

⁷⁴As

Abundance	Radioactive ☢️
Relative Atomic Mass	73.923928596 ± 0.000001817 Da
Mass Number	74
G-Factor	-0.798 ± 0.0015
Half Life	17.77 ± 0.02 d
Spin	2
Quadrupole Moment
Discovery Year	1938
Parity	-

⁷⁴As Decay Modes

Decay Mode	Intensity
β⁺ (β⁺ decay; β⁺ = ϵ + e⁺)	66%
β⁻ (β⁻ decay)	34%

⁷⁵As

Abundance	100
Relative Atomic Mass	74.921594562 ± 0.000000948 Da
Mass Number	75
G-Factor
Half Life
Spin	3/2
Quadrupole Moment	0.311 ± 0.002
Discovery Year	1920
Parity	-

⁷⁶As

Abundance	Radioactive ☢️
Relative Atomic Mass	75.922392011 ± 0.000000951 Da
Mass Number	76
G-Factor	0.45115 ± 0.0005
Half Life	1.0933 ± 0.0038 d
Spin	2
Quadrupole Moment
Discovery Year	1934
Parity	-

⁷⁶As Decay Modes

Decay Mode	Intensity
β⁻ (β⁻ decay)	100%

⁷⁷As

Abundance	Radioactive ☢️
Relative Atomic Mass	76.920647555 ± 0.000001816 Da
Mass Number	77
G-Factor	0.86266666666667 ± 0.00086666666666667
Half Life	38.79 ± 0.05 h
Spin	3/2
Quadrupole Moment
Discovery Year	1951
Parity	-

⁷⁷As Decay Modes

Decay Mode	Intensity
β⁻ (β⁻ decay)	100%

⁷⁸As

Abundance	Radioactive ☢️
Relative Atomic Mass	77.921827771 ± 0.000010498 Da
Mass Number	78
G-Factor
Half Life	90.7 ± 0.2 m
Spin	2
Quadrupole Moment
Discovery Year	1937
Parity	-

⁷⁸As Decay Modes

Decay Mode	Intensity
β⁻ (β⁻ decay)	100%

⁷⁹As

Abundance	Radioactive ☢️
Relative Atomic Mass	78.920948419 ± 0.000005716 Da
Mass Number	79
G-Factor
Half Life	9.01 ± 0.15 m
Spin	3/2
Quadrupole Moment
Discovery Year	1950
Parity	-

⁷⁹As Decay Modes

Decay Mode	Intensity
β⁻ (β⁻ decay)	100%

⁸⁰As

Abundance	Radioactive ☢️
Relative Atomic Mass	79.92247444 ± 0.000003578 Da
Mass Number	80
G-Factor
Half Life	15.2 ± 0.2 s
Spin	1
Quadrupole Moment
Discovery Year	1954
Parity	+

⁸⁰As Decay Modes

Decay Mode	Intensity
β⁻ (β⁻ decay)	100%

⁸¹As

Abundance	Radioactive ☢️
Relative Atomic Mass	80.922132288 ± 0.000002838 Da
Mass Number	81
G-Factor
Half Life	33.3 ± 0.8 s
Spin	3/2
Quadrupole Moment
Discovery Year	1960
Parity	-

⁸¹As Decay Modes

Decay Mode	Intensity
β⁻ (β⁻ decay)	100%

⁸²As

Abundance	Radioactive ☢️
Relative Atomic Mass	81.924738731 ± 0.000004003 Da
Mass Number	82
G-Factor
Half Life	19.1 ± 0.5 s
Spin	2
Quadrupole Moment
Discovery Year	1968
Parity	-

⁸²As Decay Modes

Decay Mode	Intensity
β⁻ (β⁻ decay)	100%

⁸³As

Abundance	Radioactive ☢️
Relative Atomic Mass	82.9252069 ± 0.000003004 Da
Mass Number	83
G-Factor
Half Life	13.4 ± 0.4 s
Spin	5/2
Quadrupole Moment
Discovery Year	1968
Parity	-

⁸³As Decay Modes

Decay Mode	Intensity
β⁻ (β⁻ decay)	100%

⁸⁴As

Abundance	Radioactive ☢️
Relative Atomic Mass	83.92930329 ± 0.000003403 Da
Mass Number	84
G-Factor
Half Life	3.16 ± 0.58 s
Spin	2
Quadrupole Moment
Discovery Year	1968
Parity	-

⁸⁴As Decay Modes

Decay Mode	Intensity
β⁻ (β⁻ decay)	100%
β⁻ n (β⁻-delayed neutron emission)	0.28%

⁸⁵As

Abundance	Radioactive ☢️
Relative Atomic Mass	84.932163658 ± 0.000003304 Da
Mass Number	85
G-Factor
Half Life	2.022 ± 0.007 s
Spin	5/2
Quadrupole Moment
Discovery Year	1967
Parity	-

⁸⁵As Decay Modes

Decay Mode	Intensity
β⁻ (β⁻ decay)	100%
β⁻ n (β⁻-delayed neutron emission)	62.6%

⁸⁶As

Abundance	Radioactive ☢️
Relative Atomic Mass	85.936701532 ± 0.000003703 Da
Mass Number	86
G-Factor
Half Life	945 ± 8 ms
Spin	1
Quadrupole Moment
Discovery Year	1973
Parity	-

⁸⁶As Decay Modes

Decay Mode	Intensity
β⁻ (β⁻ decay)	100%
β⁻ n (β⁻-delayed neutron emission)	35.5%
2n (2-neutron emission)	%

⁸⁷As

Abundance	Radioactive ☢️
Relative Atomic Mass	86.940291716 ± 0.000003204 Da
Mass Number	87
G-Factor
Half Life	492 ± 25 ms
Spin	5/2
Quadrupole Moment
Discovery Year	1970
Parity	-

⁸⁷As Decay Modes

Decay Mode	Intensity
β⁻ (β⁻ decay)	100%
β⁻ n (β⁻-delayed neutron emission)	15.4%
2n (2-neutron emission)	%

⁸⁸As

Abundance	Radioactive ☢️
Relative Atomic Mass	87.94584 ± 0.000215 Da
Mass Number	88
G-Factor
Half Life	270 ± 150 ms
Spin
Quadrupole Moment
Discovery Year	1994
Parity

⁸⁸As Decay Modes

Decay Mode	Intensity
β⁻ (β⁻ decay)	100%
β⁻ n (β⁻-delayed neutron emission)	%

⁸⁹As

Abundance	Radioactive ☢️
Relative Atomic Mass	88.950048 ± 0.000322 Da
Mass Number	89
G-Factor
Half Life
Spin	5/2
Quadrupole Moment
Discovery Year	1994
Parity	-

⁸⁹As Decay Modes

Decay Mode	Intensity
β⁻ (β⁻ decay)	%
β⁻ n (β⁻-delayed neutron emission)	%
2n (2-neutron emission)	%

⁹⁰As

Abundance	Radioactive ☢️
Relative Atomic Mass	89.955995 ± 0.000429 Da
Mass Number	90
G-Factor
Half Life
Spin
Quadrupole Moment
Discovery Year	1997
Parity

⁹⁰As Decay Modes

Decay Mode	Intensity
β⁻ (β⁻ decay)	%
β⁻ n (β⁻-delayed neutron emission)	%
2n (2-neutron emission)	%

⁹¹As

Abundance	Radioactive ☢️
Relative Atomic Mass	90.960816 ± 0.000429 Da
Mass Number	91
G-Factor
Half Life
Spin	5/2
Quadrupole Moment
Discovery Year	1997
Parity	-

⁹¹As Decay Modes

Decay Mode	Intensity
β⁻ (β⁻ decay)	%
β⁻ n (β⁻-delayed neutron emission)	%
2n (2-neutron emission)	%

⁹²As

Abundance	Radioactive ☢️
Relative Atomic Mass	91.967386 ± 0.000537 Da
Mass Number	92
G-Factor
Half Life
Spin
Quadrupole Moment
Discovery Year	1997
Parity

⁹²As Decay Modes

Decay Mode	Intensity
β⁻ (β⁻ decay)	%
β⁻ n (β⁻-delayed neutron emission)	%
2n (2-neutron emission)	%

History

Greek historian Olympiodorus of Thebes roasted arsenic sulfide and obtained white arsenic during 5th century AD. Albertus Magnus is believed to have been the first to isolate the element from a compound in 1250, by heating soap together with arsenic trisulfide. In 1649, Johann Schröder published two ways of preparing arsenic. From the Latin word arsenicum, Greek arsenikon

Discoverers	Known to the ancients.
Discovery Location
Discovery Year
Etymology (Name Origin)	Greek: arsenikon; Latin: arsenicum, (both names for yellow pigment).
Pronunciation	AR-s'n-ik (English)

Arsenic and its compounds are poisonous

Prawns are known to contain quite high levels of arsenic

Uses

The toxicity of arsenic to insects, bacteria and fungi led to its use as a wood preservative and as insecticides. Arsenic is used in bronzing, pyrotechny, and for hardening and improving the sphericity of shot. Gallium arsenide is a semiconductor used in laser diodes and LEDs. Small amounts of arsenic can be used in lead alloys for ammunition. Many of its compounds are deadly poison and used as weed killer and rat poison. Conducts electricity. Used in semiconductors. Some compounds, called arsenides, are used in the manufacture of paints, wallpapers, and ceramics.

Sources

Found in mispickel (arsenopyrite)

Abundance
Abundance in Earth's crust	1.8 mg/kg
Abundance in Oceans	0.0037 mg/L
Abundance in Human Body	0.000005 %
Abundance in Meteor	0.00018 %
Abundance in Sun
Abundance in Universe	0.0000008 %

Nuclear Screening Constants

1	s	0.7217
2	p	3.9264
2	s	8.873
3	d	15.6216
3	p	15.1503
3	s	14.4045
4	p	25.5508
4	s	24.056

Arsenic on ChemicalAid

Australian Educational Vocabulary ID	scot/1661
BNCF Thesaurus ID	25597
Banglapedia ID (Bengali)	আর্সেনিক
Bibliothèque nationale de France ID	11971740q
Brockhaus Enzyklopädie online ID	arsen
CAB ID	43961
CA PROP 65 ID	arsenic
CAS Registry Number	7440-38-2
ChEBI ID	27563
ChemSpider ID	4514330
DSSTOX compound identifier	DTXCID703886
DSSTox substance ID	DTXSID4023886
De Agostini ID	arsènico+(sostantivo)
Den Store Danske ID	arsen
ECHA Substance Infocard ID	100.028.316
Encyclopedia of China Online Database ID (Second Edition)	229020
Encyclopædia Universalis ID	arsenic-toxicologie
Encyclopædia Universalis ID	arsenic
Encyclopédie berbère article ID	2598
Freebase ID	/m/027rq1r
French Vikidia ID	Arsenic
GND ID	4003041-6
Gran Enciclopèdia Catalana ID	0005554
Great Russian Encyclopedia Online ID	2241159
Gujarati Vishwakosh entry	આર્સેનિક
HCIS ID	287
HSDB ID	509
ICSC ID	0013
InChI	InChI=1S/As
InChIKey	RQNWIZPPADIBDY-UHFFFAOYSA-N
KBpedia ID	Arsenic
KEGG ID	C06269
LNB ID	000306779
Library of Congress authority ID	sh85007449
LiverTox ID	Arsenic
MeSH descriptor ID	D001151
NALT ID	12370
NDF-RT ID	N0000022206
NE.se ID	arsenik
NKCR AUT ID	ph138910
National Diet Library ID	00563271
National Library of Israel J9U ID	987007294803405171
OmegaWiki Defined Meaning	255
OpenAlex ID	C502230775
OpenAlex ID	C2910930242
PACTOLS thesaurus ID	pcrt5mFxzmQ9rX
PM20 ware ID	142006
PSH ID	5803
PubChem CID	5359596
Quora topic ID	Arsenic-As
RxNorm ID	1111
Spanish Cultural Heritage thesauri ID	materias/1009757
Store medisinske leksikon ID	arsen
Store norske leksikon ID	arsen
Treccani ID	arsenico
U.S. National Archives Identifier	10637420
UK Archival Thesaurus ID	f2/mt225/4347/7620
UMLS CUI	C0003818
UNII	N712M78A8G
WikiSkripta ID	32671
Wolfram Language entity code	Entity["Mineral", "Arsenic"]
WordNet 3.1 Synset ID	14653327-n
YSO ID	9329
ZVG number	8280

Arsenic (As)

Properties

Isotopes of Arsenic

60As

60As Decay Modes

61As

61As Decay Modes

62As

62As Decay Modes

63As

63As Decay Modes

64As

64As Decay Modes

65As

65As Decay Modes

66As

66As Decay Modes

67As

67As Decay Modes

68As

68As Decay Modes

69As

69As Decay Modes

70As

70As Decay Modes

71As

71As Decay Modes

72As

72As Decay Modes

73As

73As Decay Modes

74As

74As Decay Modes

75As

76As

76As Decay Modes

77As

77As Decay Modes

78As

78As Decay Modes

79As

79As Decay Modes

80As

80As Decay Modes

81As

81As Decay Modes

82As

82As Decay Modes

83As

83As Decay Modes

84As

84As Decay Modes

85As

85As Decay Modes

86As

86As Decay Modes

87As

87As Decay Modes

88As

88As Decay Modes

89As

89As Decay Modes

90As

90As Decay Modes

91As

91As Decay Modes

92As

92As Decay Modes