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 Enhanced Bohr Model Bohr Model Orbital Diagram

Properties

Atomic Radius
115 pm
Atomic 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
Boiling Point
876 K
Melting Point
1,090 K
Electrons per shell2, 8, 18, 5
Electronegativity
2.18
Electrophilicity
1.5610969532554 eV/particle
Proton Affinity
Electron Affinity
Ionization Potential
Heat of Vaporization
32.4 kJ/mol
Heat of Fusion
Heat of Formation
302.5 kJ/mol
Molar Heat Capacity
24.64 J/(mol K)
Specific Heat Capacity
0.329 J/(g⋅K)
Thermal Conductivity
Gas Basicity
Dipole Polarizability
30 a₀
C6 Dispersion Coefficient
246 a₀
Oxidation States-3, 2, 3, 5
Color
Silver
Crystal StructureSimple Trigonal (RHL)
Lattice Constant
4.13 Å
Bulk Modulus
Electrical Resistivity
Electron Configuration[Ar] 3d10 4s2 4p3
Magnetic Ordering
Magnetic Susceptibility
PhaseSolid
Poisson Ratio
Shear Modulus
Young's Modulus
Allotropes
Alternate Names
Adiabatic Index
Appearance
Electric Conductivity
Critical Pressure
Critical Temperature
Curie Point
Electrical
Hardness
Magnetic Susceptibility
Magnetic
Neel Point
Neutron Cross Section
Neutron Mass Absorption
Gas Phase
Quantum Numbers
Refractive Index
Space Group
Speed of Sound
Superconducting Point
Thermal Expansion
Valence Electrons
Classification
CategoryMetalloids, Metalloids
CAS GroupVB
IUPAC GroupVA
Glawe Number90
Mendeleev Number95
Pettifor Number89
Geochemical Classsemi-volatile
Goldschmidt Classchalcophile
Radioactivity
RadioactiveNo
Decay Mode
Half-Life
Lifetime
Abundance
Abundance in Earth's crust
1.8 mg/kg
Abundance in Oceans
0.0037 mg/L
Abundance in Human Body
Abundance in Meteor
Abundance in Sun
Abundance in Universe8×10-7%

Isotopes of Arsenic

Stable Isotopes
75As
Unstable Isotopes
60As 61As 62As 63As 64As 65As 66As 67As 68As 69As 70As 71As 72As 73As 74As 76As 77As 78As 79As 80As 81As 82As 83As 84As 85As 86As 87As 88As 89As 90As 91As 92As

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
Name OriginGreek: arsenikon; Latin: arsenicum, (both names for yellow pigment).
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)