Arsenic (As)
metalloidSolid
Peso atómico estándar
74,921595 uConfiguración electrónica
[Ar] 4s2 3d10 4p3Punto de fusión
816,85 °CPunto de ebullición
613,85 °CDensidad
5776 kg/m³Estados de oxidación
−3, −2, −1, 0, +1, +2, +3, +4, +5Electronegatividad (Pauling)
2,18Energía de ionización (1.ª)
9,78855 eVAño de descubrimiento
1250Radio atómico
115 pmDetalles
Arsenic is a metalloid in group 15, chemically related to phosphorus and antimony. It occurs mainly in sulfide minerals and in arsenide or sulfosalt ores, rather than as the native element. Its chemistry is dominated by the +3 and +5 oxidation states, with important differences in mobility and toxicity among species. Arsenic is technologically useful in small quantities, especially in compound semiconductors, but it is better known for the toxicity of many of its inorganic compounds.
The element is a steel gray, very brittle, crystalline, semimetallic solid; it tarnishes in air, and when it is heated it rapidly oxidizes to arsenous oxide, which smells of garlic. Arsenic and its compounds are poisonous.
The name derives from the Latin arsenicium and the Greek arsenikos for "masculine" or "male" because the ancients thought that metals were different sexes. Arsenic was known in prehistoric times for its poisonous sulfides. The German scientist and philosopher, Albert von Bollstadt (Albert the Great or Albertus Magnus) is thought to have obtained the metal around 1250.
Although arsenic compounds were mined by the early Chinese, Greek and Egyptian civilizations, it is believed that arsenic itself was first identified by Albertus Magnus, a German alchemist, in 1250. Arsenic occurs free in nature, but is most often found in the minerals arsenopyrite (FeAsS), realgar (AsS) and orpiment (As2S3). Today, most commercial arsenic is obtained by heating arsenopyrite.
From the Latin word arsenicum, Greek arsenikon. Elemental arsenic occurs in two solid modifications: yellow, and gray or metallic, with specific gravities of 1.97, and 5.73, respectively. It is believed that Albertus Magnus obtained the element in 1250 A.D. In 1649 Schroeder published two methods of preparing the element. Mispickel arsenopyrite, (FeSAs), is the most common mineral from which, on heating, the arsenic sublimes leaving ferrous sulfide.
Pure arsenic is most commonly encountered as gray arsenic, a brittle, metallic-looking solid with a steel-gray surface. It sublimes readily on heating rather than melting at ordinary pressure. Yellow and black allotropes are known but are less stable under ordinary conditions.
Elemental arsenic has limited direct use. Small additions have been used to harden lead alloys, especially for shot, grids, and some bearing materials. The most important modern use is in high-purity compound semiconductors, notably gallium arsenide (GaAs), which is used in radio-frequency electronics, optoelectronics, infrared devices, and some high-efficiency solar cells. Arsenic compounds were formerly used widely in pesticides, herbicides, wood preservatives, pigments, and medicines, but many such uses have been restricted or abandoned because of toxicity and persistence.
Arsenic and its compounds are poisonous. They have been used to make rat poison and some insecticides. Small amounts of arsenic are added to germanium to make transistors. Gallium arsenide (GaAs) can produce laser light directly from electricity.
If you were paying careful attention to the physical data listed above, you may have noticed that arsenic's boiling point is lower than its melting point. This occurs because these two temperatures are measured at different atmospheric pressures. When heated at standard atmospheric pressure, arsenic changes directly from a solid to a gas, or sublimates, at a temperature of 887 K. In order to form liquid arsenic, the atmospheric pressure must be increased. At 28 times standard atmospheric pressure, arsenic melts at a temperature of 1090 K. If it were also measured at a pressure of 28 atmospheres, arsenic's boiling point would be higher than its melting point, as you would expect.
Arsenic is used in bronzing, pyrotechny, and for hardening and improving the sphericity of shot. The most important compounds are white arsenic, the sulfide, Paris green, calcium arsenate, and lead arsenate; the last three have been used as agricultural insecticides and poisons. Marsh's test makes use of the formation and ready decomposition of arsine. Arsenic is finding increasing uses as a doping agent in solid-state devices such as transistors. Gallium arsenide is used as a laser material to convert electricity directly into coherent light.
Isotopes in Biology
73As and 76As (with half-lives of 80.3 days and 1.1 days, respectively) are important radioactive tracers used in environmental and biomedical studies to quantify arsenic uptake [270] J. De Kimpe, R. Cornelis, L. Mees, R. Vanholder. Fundam. Appl. Toxicol.34, 240 (1996).. 74As (with a half-life of 17.8 days) has been used to investigate the biotransformation (modification of a chemical compound by an organism) of arsenate by mammals. In one study rabbits were injected with 74As-labeled arsenate. After a given amount of time, blood and blood products were sampled and tested for the presence and quantity of labeled arsenate metabolites [270] J. De Kimpe, R. Cornelis, L. Mees, R. Vanholder. Fundam. Appl. Toxicol.34, 240 (1996).. Inhalation of dust or smoke containing 74As is thought to be a causal agent of lung cancer. In one study [271] R. H. Holland, M. S. McCall, H. C. Lanz. Cancer Res.19, 1154 (1959)., the “absorption rate from the bronchial tree (a respiratory tract, which conducts air into the lungs) was rapid for the first several days and then tapered off slowly. In three patients an average of 45 percent of the inhaled arsenic was eliminated in the urine in 10 days and about 0.5 percent in the stools. The remainder must be assumed to have been deposited in the body, exhaled, and/or eliminated in body secretions and excreta over a long period of time.” See Fig. IUPAC.33.1.
Isotopes in Medicine
72As (with a half-life of 26 h) and 74As are useful in molecular imaging because they are radioactive isotopes that emit positrons that can be designed to bind to monoclonal antibodies (moAb), which accumulate in tumors and then 72As- or 74As-labeled ligands will bind to the moAbs. Once the 72As- or 74As-labeled ligand binds to the moAb, positron emission tomography (PET) is used to visualize the exact location of the tumor [272] M. Jennewein, A. Hermanne, R. P. Mason, P. E. Thorpe, F. Rösch. Nucl. Instrum. Methods Phys. Res. A569, 512 (2006).. A specific example of using radiolabeled antibodies for better imaging of tumors is the combination of 74As with bavituximab, which is an antibody that binds strongly to unique lipids on the surface of tumors. When a thiol group is introduced to bavituximab, arsenic is able to bind covalently, creating a simple and elegant radio-label for targeting cancerous tumors [269] M. Jennewein, M. A. Lewis, D. Zhao, E. Tsyganov, N. Slavine, J. He, L. Watkins, V. D. Kodibagkar, S. O’Kelly, P. Kulkarni, P. P. Antich, A. Hermanne, F. Rösch, R. P. Mason, P. E. Thorpe. Clin. Cancer Res.14, 1377 (2008)..
Arsenic forms covalent and ionic compounds in several oxidation states, chiefly −3, +3, and +5. Arsenic trioxide (As₂O₃) is a major industrial intermediate and dissolves to give arsenite species. Arsenic pentoxide (As₂O₅) and arsenic acid (H₃AsO₄) contain arsenic in the +5 state and are related to arsenate salts. Arsine (AsH₃) is a highly toxic, volatile hydride. Important minerals include arsenopyrite (FeAsS), realgar (As₄S₄), and orpiment (As₂S₃). Organoarsenic compounds also exist, including methylated species found in biological and environmental systems.
See more information at the Arsenic compound page.
Arsenic metal is hazardous mainly through dust, fumes, and conversion to soluble or volatile compounds. Many inorganic arsenic(III) compounds are acutely toxic, and chronic exposure to inorganic arsenic in drinking water or industrial settings is associated with serious disease, including cancers. Arsine (AsH₃) is especially dangerous because it is a potent hemolytic gas. Toxicity depends strongly on chemical form, dose, route of exposure, and solubility; organic arsenic species in seafood are often much less toxic than inorganic arsenic.
Arsenic enters the environment through natural weathering of minerals, volcanic emissions, geothermal waters, and human activities such as mining, smelting, coal combustion, and historical pesticide use. In groundwater, its mobility is controlled by pH, redox conditions, adsorption to iron and manganese oxides, and microbial transformations. Arsenate species generally predominate under oxidizing conditions, while arsenite species are more important under reducing conditions and are often more mobile and toxic.
Arsenic is not usually mined as a primary commodity. It is recovered mainly as arsenic trioxide (As₂O₃) from flue dusts and residues generated during the smelting and refining of copper, lead, gold, and other nonferrous ores. Demand is much smaller than in the past because agricultural chemicals and chromated copper arsenate wood preservatives have been reduced or phased out in many regions. High-purity arsenic for gallium arsenide (GaAs) is a specialized market requiring stringent purification. Supply depends heavily on by-product recovery, environmental controls at smelters, and the ability to handle or stabilize arsenic-bearing wastes.
Found in mispickel (arsenopyrite)
Arsenic is a relatively uncommon element in the cosmos. Its stable isotope, ⁷⁵As, is produced by neutron-capture processes in evolved stars and supernova-related environments. In planetary materials, arsenic behaves as a moderately chalcophile and siderophile trace element, so it is commonly associated with sulfides and metallic phases rather than silicate minerals alone. Meteorites contain small amounts of arsenic in mineral and metal fractions.
- Natural arsenic consists essentially of one stable isotope, ⁷⁵As.
- Gray arsenic sublimes at ordinary pressure, which complicates simple melting-point measurements.
- Garlic-like odor during heating often comes from volatile arsenic compounds, not a safe warning sign.
- Arsenopyrite (FeAsS) is one of the most important arsenic-bearing ore minerals.
- Gallium arsenide (GaAs) has higher electron mobility than silicon, but it is costlier and more brittle.
- Some microorganisms can transform arsenic between arsenite, arsenate, and methylated forms.
Imágenes
Propiedades
Físicas
- Radio atómico (empírico)
- 115 pm Comparar Radio atómico (empírico) de todos los elementos →
- Radio covalente
- 119 pm Comparar Radio covalente de todos los elementos →
- Radio de van der Waals
- 185 pm Comparar Radio de van der Waals de todos los elementos →
- Radio metálico
- 121 pm Comparar Radio metálico de todos los elementos →
- Densidad
- 5776 kg/m³ Comparar Densidad de todos los elementos →
- Volumen molar
- 0,0131 L/mol
- Fase en CNPT
- Sólido Comparar Fase en CNPT de todos los elementos →
- Punto de fusión
- 816,85 °C Comparar Punto de fusión de todos los elementos →
- Punto de ebullición
- 613,85 °C Comparar Punto de ebullición de todos los elementos →
- Capacidad calorífica específica
- 0,329 J/(g·K) Comparar Capacidad calorífica específica de todos los elementos →
- Capacidad calorífica molar
- 24,64 J/(mol·K) Comparar Capacidad calorífica molar de todos los elementos →
- Estructura cristalina
- Romboédrica Comparar Estructura cristalina de todos los elementos →
Químicas
- Electronegatividad (Pauling)
- 2,18 Comparar Electronegatividad (Pauling) de todos los elementos →
- Electronegatividad (Allen)
- 2,211
- Afinidad electrónica
- 0,81 eV
- Energía de ionización (1.ª)
- 9,78855 eV Comparar Energía de ionización (1.ª) de todos los elementos →
- Energía de ionización (2.ª)
- 18,589264 eV Comparar Energía de ionización (2.ª) de todos los elementos →
- Energía de ionización (3.ª)
- 28,349098 eV Comparar Energía de ionización (3.ª) de todos los elementos →
- Energía de ionización (4.ª)
- 50,150173 eV Comparar Energía de ionización (4.ª) de todos los elementos →
- Energía de ionización (5.ª)
- 62,770216 eV Comparar Energía de ionización (5.ª) de todos los elementos →
- Estados de oxidación
- −3, −2, −1, 0, +1, +2, +3, +4, +5 Comparar Estados de oxidación de todos los elementos →
- Electrones de valencia
- 5 Comparar Electrones de valencia de todos los elementos →
- Alótropos
- ["gray"]
- Configuración electrónica
- [Ar] 4s2 3d10 4p3
Termodinámicas
- Punto triple (temperatura)
- 817 °C
- Punto triple (presión)
- 3,7e+6 Pa
- Punto crítico (temperatura)
- 1400 °C
- Punto crítico (presión)
- 2,23e+7 Pa
- Calor de vaporización
- 0,36275069 eV Comparar Calor de vaporización de todos los elementos →
- Calor de sublimación
- 3,138312 eV
- Calor de atomización
- 3,138312 eV
- Entalpía de atomización
- 3,135202 eV
Nucleares
- Protones
- 33 Comparar Protones de todos los elementos →
- Neutrones
- 42 Comparar Neutrones de todos los elementos →
- Isótopos conocidos
- 33 Comparar Isótopos conocidos de todos los elementos →
- Isótopos estables
- 1 Comparar Isótopos estables de todos los elementos →
- Isótopo más estable
- As-75
- Año de descubrimiento
- 1250
Abundancia
- Abundancia (corteza terrestre)
- 1,8 mg/kg Comparar Abundancia (corteza terrestre) de todos los elementos →
- Abundancia (océano)
- 3,7 mg/L Comparar Abundancia (océano) de todos los elementos →
Estructura cristalina
- Constante de red a
- 413 pm
Estructura electrónica
- Electrones por capa
- 2, 8, 18, 5 Comparar Electrones por capa de todos los elementos →
Identificadores
- Número CAS
- 7440-38-2 Comparar Número CAS de todos los elementos →
- Símbolo del término
- 4S°3/2
- InChI
- InChI=1S/As
- Clave InChI
- RQNWIZPPADIBDY-UHFFFAOYSA-N
Configuración electrónica Medido
As: 3d¹⁰ 4s² 4p³[Ar] 3d¹⁰ 4s² 4p³1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p³Modelo atómico
Los isótopos cambian el número de neutrones, la masa y la estabilidad, pero no la configuración electrónica de un átomo neutro.
Modelo atómico esquemático, no a escala.
Huella atómica
Espectro de emisión / absorción
Distribución isotópica
| Número másico | Masa atómica (u) | Abundancia natural | Periodo de semidesintegración |
|---|---|---|---|
| 75 Estable | 74,92159457 ± 0,00000095 | 100,0000% | Estable |
Fase / Estado
Motivo: 588,9 °C por debajo del punto de sublimación (613,85 °C)
Esquemático, no a escala
Puntos de transición de fase
Energías de transición
Energía necesaria para vaporizar 1 mol en el punto de ebullición
Energía necesaria para sublimar 1 mol en el punto de sublimación
Densidad
En condiciones estándar
En condiciones estándar
Avanzado
Espectros atómicos
Se muestran 10 de 33. Ordenado por carga del ion (ascendente).
Líneas disponibles ?
| Ion | Carga | Total de líneas | Probabilidades de transición | Designaciones de los niveles |
|---|---|---|---|---|
| As I | 0 | 52 | 14 | 51 |
| As II | +1 | 86 | 0 | 0 |
| As III | +2 | 14 | 0 | 0 |
| As IV | +3 | 8 | 0 | 0 |
| As V | +4 | 9 | 0 | 0 |
Niveles disponibles ?
| Ion | Carga | Niveles |
|---|---|---|
| As I | 0 | 116 |
| As II | +1 | 167 |
| As III | +2 | 22 |
| As IV | +3 | 34 |
| As V | +4 | 9 |
| As VI | +5 | 44 |
| As VII | +6 | 50 |
| As VIII | +7 | 2 |
| As IX | +8 | 2 |
| As X | +9 | 2 |
Radios iónicos
| Carga | Coordinación | Espín | Radio |
|---|---|---|---|
| +3 | 6 | N/D | 57.99999999999999 pm |
| +5 | 4 | N/D | 33.5 pm |
| +5 | 6 | N/D | 46 pm |
Compuestos
Isótopos (1)
| Número másico | Masa atómica (u) | Abundancia natural | Periodo de semidesintegración | Modo de desintegración | |
|---|---|---|---|---|---|
| 75 Estable | 74,92159457 ± 0,00000095 | 100,0000% | Estable | stable |
Propiedades ampliadas
Radios covalentes (ampliados)
- Radio covalente (Pyykkö)
- 121 pm
- Radio covalente (Pyykkö, enlace doble)
- 114 pm
- Radio covalente (Pyykkö, enlace triple)
- 106 pm
- Radio covalente (Bragg)
- 126 pm
Radios de van der Waals
- Bondi
- 185 pm
- Batsanov
- 205 pm
- Alvarez
- 188 pm
- UFF
- 423 pm
- MM3
- 236 pm
- Dreiding
- 415 pm
Radios atómicos y metálicos
- Radio atómico (Rahm)
- 231 pm
- Radio metálico (C12)
- 148 pm
Escalas de numeración
- Mendeleev
- 95
- Pettifor
- 89
- Glawe
- 90
Escalas de electronegatividad
- Ghosh
- 0
- Miedema
- 5
- Gunnarsson–Lundqvist
- 5
- Robles–Bartolotti
- 4
Polarizabilidad y dispersión
- Polarizabilidad dipolar
- 30 a.u.
- Polarizabilidad dipolar (incert.)
- 1 a.u.
- C₆
- 246 Ha·Bohr6
- C₆ (Gould–Bučko)
- 260 Ha·Bohr6
Parámetros de Miedema
- Volumen molar de Miedema
- 11,85 cm3/mol
- Densidad electrónica de Miedema
- 3
Riesgo de suministro y economía
- Concentración de la producción
- 64
- Riesgo relativo de suministro
- 8
- Estabilidad política (principal productor)
- 24
Transiciones de fase y alótropos
| Punto de fusión | 1090,15 K |
| Punto de ebullición | 889,15 K |
| Punto crítico (temperatura) | 1673,15 K |
| Punto crítico (presión) | 22,3 MPa |
| Punto triple (temperatura) | 1090,15 K |
| Punto triple (presión) | 3700 kPa |
Categorías de estados de oxidación
Datos de referencia avanzados
Constantes de apantallamiento (8)
| n | Orbital | σ |
|---|---|---|
| 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 |
Detalle de los radios cristalinos (3)
| Carga | CN | Espín | rcrystal (pm) | Origen |
|---|---|---|---|---|
| 3 | VI | 72 | Ahrens (1952) ionic radius, | |
| 5 | IV | 47,5 | from r^3 vs V plots, | |
| 5 | VI | 60 | calculated, |
Modos de desintegración de los isótopos (50)
| Isótopo | Modo | Intensidad |
|---|---|---|
| 60 | p | — |
| 61 | p | — |
| 62 | p | — |
| 63 | p | — |
| 64 | B+ | 100% |
| 64 | B+p | — |
| 65 | B+ | 100% |
| 65 | B+p | — |
| 66 | B+ | 100% |
| 67 | B+ | 100% |
Factores de dispersión de rayos X (506)
| Energía (eV) | f₁ | f₂ |
|---|---|---|
| 10 | — | 4,62596 |
| 10,1617 | — | 4,67742 |
| 10,3261 | — | 4,72945 |
| 10,4931 | — | 4,78206 |
| 10,6628 | — | 4,83525 |
| 10,8353 | — | 4,88904 |
| 11,0106 | — | 4,94342 |
| 11,1886 | — | 4,99841 |
| 11,3696 | — | 5,05401 |
| 11,5535 | — | 5,11023 |
Datos adicionales
Estimated Crustal Abundance
The estimated element abundance in the earth's crust.
1.8 milligrams per kilogram
Referencias (1)
Estimated Oceanic Abundance
The estimated element abundance in the earth's oceans.
3.7-3 milligrams per liter
Referencias (1)
Referencias
(9)
Data deposited in or computed by PubChem
The half-life and atomic mass data was provided by the Atomic Mass Data Center at the International Atomic Energy Agency.
Element data are cited from the Atomic weights of the elements (an IUPAC Technical Report). The IUPAC periodic table of elements can be found at https://iupac.org/what-we-do/periodic-table-of-elements/. Additional information can be found within IUPAC publication doi:10.1515/pac-2015-0703 Copyright © 2020 International Union of Pure and Applied Chemistry.
The information are cited from Pure Appl. Chem. 2018; 90(12): 1833-2092, https://doi.org/10.1515/pac-2015-0703.
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The periodic table at the LANL (Los Alamos National Laboratory) contains basic element information together with the history, source, properties, use, handling and more. The provenance data may be found from the link under the source name.
The periodic table contains NIST's critically-evaluated data on atomic properties of the elements. The provenance data that include data for atomic spectroscopy, X-ray and gamma ray, radiation dosimetry, nuclear physics, and condensed matter physics may be found from the link under the source name. Ref: https://www.nist.gov/pml/atomic-spectra-database
This section provides all form of data related to element Arsenic.
The element property data was retrieved from publications.