Arsenic

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 Number33
Atomic Weight74.921595
Mass Number75
Group15
Period4
Blockp
Protons33 p+
Neutrons42 n0
Electrons33 e-
Arsen 1.jpg Animated Bohr Model of As (Arsenic) Enhanced Bohr Model of As (Arsenic) Bohr Model: As (Arsenic) Orbital Diagram of As (Arsenic)

Properties

Atomic Radius
115 pm
Molar Volume
Covalent Radius
121 pm
Metallic Radius
121 pm
Ionic Radius
58 pm
Crystal Radius
72 pm
Van der Waals Radius
185 pm
Density
5.75 g/cm³
Energy
Proton Affinity
Electron Affinity
Ionization Energy
Heat of Vaporization
32.4 kJ/mol
Heat of Fusion
Heat of Formation
302.5 kJ/mol
Electrons
Electron Shells2, 8, 18, 5
Valence Electrons5
Electron Configuration[Ar] 3d10 4s2 4p3
Oxidation States-3, -2, -1, 0, 1, 2, 3, 4, 5
Electronegativity
2.18
Electrophilicity
1.5610969532554257 eV/particle
Phases
PhaseSolid
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
Appearancemetallic 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
TypeConductor
Electrical Conductivity
3.3 MS/m
Electrical Resistivity
0.0000003 m Ω
Superconducting Point
Magnetism
Typediamagnetic
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 StructureSimple Trigonal (RHL)
Lattice Constant
4.13 Å
Lattice Anglesπ/2, π/2, 2 π/3
Mechanical Properties
Hardness
3.5 MPa
Bulk Modulus
22 GPa
Shear Modulus
Young Modulus
8 GPa
Poisson Ratio
Speed of Sound
Classification
CategoryMetalloids, Metalloids
CAS GroupVB
IUPAC GroupVA
Glawe Number90
Mendeleev Number95
Pettifor Number89
Geochemical Classsemi-volatile
Goldschmidt Classchalcophile
Other
Gas Basicity
Dipole Polarizability
30 ± 1 a₀
C6 Dispersion Coefficient
246 a₀
AllotropesYellow Arsenic, Black Arsenic, Gray Arsenic
Neutron Cross Section
4.2
Neutron Mass Absorption
0.002
Quantum Numbers4S3/2
Space Group166 (R_3m)

Isotopes of Arsenic

Stable Isotopes1
Unstable Isotopes32
Radioactive Isotopes28

60As

Abundance
Relative Atomic Mass
59.993945 ± 0.000429 Da
Mass Number60
G-Factor
Half Life
Spin5
Quadrupole Moment
Discovery Year
Parity+

60As Decay Modes
Decay ModeIntensity
p (proton emission)%

61As

Abundance
Relative Atomic Mass
60.981535 ± 0.000322 Da
Mass Number61
G-Factor
Half Life
Spin3/2
Quadrupole Moment
Discovery Year
Parity-

61As Decay Modes
Decay ModeIntensity
p (proton emission)%

62As

Abundance
Relative Atomic Mass
61.973784 ± 0.000322 Da
Mass Number62
G-Factor
Half Life
Spin1
Quadrupole Moment
Discovery Year
Parity+

62As Decay Modes
Decay ModeIntensity
p (proton emission)%

63As

Abundance
Relative Atomic Mass
62.964036 ± 0.000215 Da
Mass Number63
G-Factor
Half Life
Spin3/2
Quadrupole Moment
Discovery Year
Parity-

63As Decay Modes
Decay ModeIntensity
p (proton emission)%

64As

AbundanceRadioactive ☢️
Relative Atomic Mass
63.95756 ± 0.000218 Da
Mass Number64
G-Factor
0
Half Life
69 ± 1.4 ms
Spin0
Quadrupole Moment
0
Discovery Year1995
Parity+

64As Decay Modes
Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)100%
β+ p (β+-delayed proton emission)%

65As

AbundanceRadioactive ☢️
Relative Atomic Mass
64.949611 ± 0.000091 Da
Mass Number65
G-Factor
Half Life
130.3 ± 0.6 ms
Spin3/2
Quadrupole Moment
Discovery Year1991
Parity-

65As Decay Modes
Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)100%
β+ p (β+-delayed proton emission)%

66As

AbundanceRadioactive ☢️
Relative Atomic Mass
65.944148778 ± 0.0000061 Da
Mass Number66
G-Factor
0
Half Life
95.77 ± 0.23 ms
Spin0
Quadrupole Moment
0
Discovery Year1978
Parity+

66As Decay Modes
Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)100%

67As

AbundanceRadioactive ☢️
Relative Atomic Mass
66.93925111 ± 0.000000475 Da
Mass Number67
G-Factor
Half Life
42.5 ± 1.2 s
Spin5/2
Quadrupole Moment
Discovery Year1980
Parity-

67As Decay Modes
Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)100%

68As

AbundanceRadioactive ☢️
Relative Atomic Mass
67.936774127 ± 0.000001981 Da
Mass Number68
G-Factor
Half Life
151.6 ± 0.8 s
Spin3
Quadrupole Moment
Discovery Year1971
Parity+

68As Decay Modes
Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)100%

69As

AbundanceRadioactive ☢️
Relative Atomic Mass
68.932246289 ± 0.000034352 Da
Mass Number69
G-Factor
0.6488 ± 0.0008
Half Life
15.2 ± 0.2 m
Spin5/2
Quadrupole Moment
Discovery Year1955
Parity-

69As Decay Modes
Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)100%

70As

AbundanceRadioactive ☢️
Relative Atomic Mass
69.930934642 ± 0.0000015 Da
Mass Number70
G-Factor
0.5276 ± 0.000125
Half Life
52.6 ± 0.3 m
Spin4
Quadrupole Moment
0.09 ± 0.02
Discovery Year1950
Parity+

70As Decay Modes
Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)100%

71As

AbundanceRadioactive ☢️
Relative Atomic Mass
70.927113594 ± 0.000004469 Da
Mass Number71
G-Factor
0.6692 ± 0.0008
Half Life
65.3 ± 0.07 h
Spin5/2
Quadrupole Moment
-0.021 ± 0.006
Discovery Year1939
Parity-

71As Decay Modes
Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)100%

72As

AbundanceRadioactive ☢️
Relative Atomic Mass
71.926752291 ± 0.000004383 Da
Mass Number72
G-Factor
-1.0805 ± 0.0003
Half Life
26 ± 0.1 h
Spin2
Quadrupole Moment
-0.08 ± 0.02
Discovery Year1939
Parity-

72As Decay Modes
Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)100%

73As

AbundanceRadioactive ☢️
Relative Atomic Mass
72.923829086 ± 0.000004136 Da
Mass Number73
G-Factor
Half Life
80.3 ± 0.06 d
Spin3/2
Quadrupole Moment
Discovery Year1948
Parity-

73As Decay Modes
Decay ModeIntensity
ϵ (electron capture)100%

74As

AbundanceRadioactive ☢️
Relative Atomic Mass
73.923928596 ± 0.000001817 Da
Mass Number74
G-Factor
-0.798 ± 0.0015
Half Life
17.77 ± 0.02 d
Spin2
Quadrupole Moment
Discovery Year1938
Parity-

74As Decay Modes
Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)66%
β (β decay)34%

75As

Abundance
100
Relative Atomic Mass
74.921594562 ± 0.000000948 Da
Mass Number75
G-Factor
Half Life
Spin3/2
Quadrupole Moment
0.311 ± 0.002
Discovery Year1920
Parity-

76As

AbundanceRadioactive ☢️
Relative Atomic Mass
75.922392011 ± 0.000000951 Da
Mass Number76
G-Factor
0.45115 ± 0.0005
Half Life
1.0933 ± 0.0038 d
Spin2
Quadrupole Moment
Discovery Year1934
Parity-

76As Decay Modes
Decay ModeIntensity
β (β decay)100%

77As

AbundanceRadioactive ☢️
Relative Atomic Mass
76.920647555 ± 0.000001816 Da
Mass Number77
G-Factor
0.86266666666667 ± 0.00086666666666667
Half Life
38.79 ± 0.05 h
Spin3/2
Quadrupole Moment
Discovery Year1951
Parity-

77As Decay Modes
Decay ModeIntensity
β (β decay)100%

78As

AbundanceRadioactive ☢️
Relative Atomic Mass
77.921827771 ± 0.000010498 Da
Mass Number78
G-Factor
Half Life
90.7 ± 0.2 m
Spin2
Quadrupole Moment
Discovery Year1937
Parity-

78As Decay Modes
Decay ModeIntensity
β (β decay)100%

79As

AbundanceRadioactive ☢️
Relative Atomic Mass
78.920948419 ± 0.000005716 Da
Mass Number79
G-Factor
Half Life
9.01 ± 0.15 m
Spin3/2
Quadrupole Moment
Discovery Year1950
Parity-

79As Decay Modes
Decay ModeIntensity
β (β decay)100%

80As

AbundanceRadioactive ☢️
Relative Atomic Mass
79.92247444 ± 0.000003578 Da
Mass Number80
G-Factor
Half Life
15.2 ± 0.2 s
Spin1
Quadrupole Moment
Discovery Year1954
Parity+

80As Decay Modes
Decay ModeIntensity
β (β decay)100%

81As

AbundanceRadioactive ☢️
Relative Atomic Mass
80.922132288 ± 0.000002838 Da
Mass Number81
G-Factor
Half Life
33.3 ± 0.8 s
Spin3/2
Quadrupole Moment
Discovery Year1960
Parity-

81As Decay Modes
Decay ModeIntensity
β (β decay)100%

82As

AbundanceRadioactive ☢️
Relative Atomic Mass
81.924738731 ± 0.000004003 Da
Mass Number82
G-Factor
Half Life
19.1 ± 0.5 s
Spin2
Quadrupole Moment
Discovery Year1968
Parity-

82As Decay Modes
Decay ModeIntensity
β (β decay)100%

83As

AbundanceRadioactive ☢️
Relative Atomic Mass
82.9252069 ± 0.000003004 Da
Mass Number83
G-Factor
Half Life
13.4 ± 0.4 s
Spin5/2
Quadrupole Moment
Discovery Year1968
Parity-

83As Decay Modes
Decay ModeIntensity
β (β decay)100%

84As

AbundanceRadioactive ☢️
Relative Atomic Mass
83.92930329 ± 0.000003403 Da
Mass Number84
G-Factor
Half Life
3.16 ± 0.58 s
Spin2
Quadrupole Moment
Discovery Year1968
Parity-

84As Decay Modes
Decay ModeIntensity
β (β decay)100%
β n (β-delayed neutron emission)0.28%

85As

AbundanceRadioactive ☢️
Relative Atomic Mass
84.932163658 ± 0.000003304 Da
Mass Number85
G-Factor
Half Life
2.022 ± 0.007 s
Spin5/2
Quadrupole Moment
Discovery Year1967
Parity-

85As Decay Modes
Decay ModeIntensity
β (β decay)100%
β n (β-delayed neutron emission)62.6%

86As

AbundanceRadioactive ☢️
Relative Atomic Mass
85.936701532 ± 0.000003703 Da
Mass Number86
G-Factor
Half Life
945 ± 8 ms
Spin1
Quadrupole Moment
Discovery Year1973
Parity-

86As Decay Modes
Decay ModeIntensity
β (β decay)100%
β n (β-delayed neutron emission)35.5%
2n (2-neutron emission)%

87As

AbundanceRadioactive ☢️
Relative Atomic Mass
86.940291716 ± 0.000003204 Da
Mass Number87
G-Factor
Half Life
492 ± 25 ms
Spin5/2
Quadrupole Moment
Discovery Year1970
Parity-

87As Decay Modes
Decay ModeIntensity
β (β decay)100%
β n (β-delayed neutron emission)15.4%
2n (2-neutron emission)%

88As

AbundanceRadioactive ☢️
Relative Atomic Mass
87.94584 ± 0.000215 Da
Mass Number88
G-Factor
Half Life
270 ± 150 ms
Spin
Quadrupole Moment
Discovery Year1994
Parity

88As Decay Modes
Decay ModeIntensity
β (β decay)100%
β n (β-delayed neutron emission)%

89As

AbundanceRadioactive ☢️
Relative Atomic Mass
88.950048 ± 0.000322 Da
Mass Number89
G-Factor
Half Life
Spin5/2
Quadrupole Moment
Discovery Year1994
Parity-

89As Decay Modes
Decay ModeIntensity
β (β decay)%
β n (β-delayed neutron emission)%
2n (2-neutron emission)%

90As

AbundanceRadioactive ☢️
Relative Atomic Mass
89.955995 ± 0.000429 Da
Mass Number90
G-Factor
Half Life
Spin
Quadrupole Moment
Discovery Year1997
Parity

90As Decay Modes
Decay ModeIntensity
β (β decay)%
β n (β-delayed neutron emission)%
2n (2-neutron emission)%

91As

AbundanceRadioactive ☢️
Relative Atomic Mass
90.960816 ± 0.000429 Da
Mass Number91
G-Factor
Half Life
Spin5/2
Quadrupole Moment
Discovery Year1997
Parity-

91As Decay Modes
Decay ModeIntensity
β (β decay)%
β n (β-delayed neutron emission)%
2n (2-neutron emission)%

92As

AbundanceRadioactive ☢️
Relative Atomic Mass
91.967386 ± 0.000537 Da
Mass Number92
G-Factor
Half Life
Spin
Quadrupole Moment
Discovery Year1997
Parity

92As Decay Modes
Decay ModeIntensity
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

DiscoverersKnown to the ancients.
Discovery Location
Discovery Year
Etymology (Name Origin)Greek: arsenikon; Latin: arsenicum, (both names for yellow pigment).
PronunciationAR-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

1s0.7217
2p3.9264
2s8.873
3d15.6216
3p15.1503
3s14.4045
4p25.5508
4s24.056