Arsenic (As)
metalloidSolid
標準原子量
74.921595 u電子配置
[Ar] 4s2 3d10 4p3融点
816.85 °C沸点
613.85 °C密度
5776 kg/m³酸化数
−3, −2, −1, 0, +1, +2, +3, +4, +5電気陰性度（Pauling）
2.18第1イオン化エネルギー
9.78855 eV発見年
1250原子半径
115 pm詳細
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.
画像
性質
物理的性質
- 原子半径（経験値）
- 115 pm 全元素の原子半径（経験値）を比較 →
- 共有結合半径
- 119 pm 全元素の共有結合半径を比較 →
- ファンデルワールス半径
- 185 pm 全元素のファンデルワールス半径を比較 →
- 金属半径
- 121 pm 全元素の金属半径を比較 →
- 密度
- 5776 kg/m³ 全元素の密度を比較 →
- モル体積
- 0.0131 L/mol
- 標準温度・圧力（STP）での相
- 固体 全元素の標準温度・圧力（STP）での相を比較 →
- 融点
- 816.85 °C 全元素の融点を比較 →
- 沸点
- 613.85 °C 全元素の沸点を比較 →
- 比熱容量
- 0.329 J/(g·K) 全元素の比熱容量を比較 →
- モル熱容量
- 24.64 J/(mol·K) 全元素のモル熱容量を比較 →
- 結晶構造
- 菱面体構造 全元素の結晶構造を比較 →
化学的性質
- 電気陰性度（Pauling）
- 2.18 全元素の電気陰性度（Pauling）を比較 →
- 電気陰性度（Allen）
- 2.211
- 電子親和力
- 0.81 eV
- 第1イオン化エネルギー
- 9.78855 eV 全元素の第1イオン化エネルギーを比較 →
- 第2イオン化エネルギー
- 18.589264 eV 全元素の第2イオン化エネルギーを比較 →
- 第3イオン化エネルギー
- 28.349098 eV 全元素の第3イオン化エネルギーを比較 →
- 第4イオン化エネルギー
- 50.150173 eV 全元素の第4イオン化エネルギーを比較 →
- 第5イオン化エネルギー
- 62.770216 eV 全元素の第5イオン化エネルギーを比較 →
- 酸化数
- −3, −2, −1, 0, +1, +2, +3, +4, +5 全元素の酸化数を比較 →
- 価電子
- 5 全元素の価電子を比較 →
- 同素体
- ["gray"]
- 電子配置
- [Ar] 4s2 3d10 4p3
熱力学的性質
- 三重点（温度）
- 817 °C
- 三重点（圧力）
- 3.7e+6 Pa
- 臨界点（温度）
- 1400 °C
- 臨界点（圧力）
- 2.23e+7 Pa
- 蒸発熱
- 0.36275069 eV 全元素の蒸発熱を比較 →
- 昇華熱
- 3.138312 eV
- 原子化熱
- 3.138312 eV
- 原子化エンタルピー
- 3.135202 eV
原子核
- 陽子数
- 33 全元素の陽子数を比較 →
- 中性子数
- 42 全元素の中性子数を比較 →
- 既知の同位体
- 33 全元素の既知の同位体を比較 →
- 安定同位体
- 1 全元素の安定同位体を比較 →
- 最も安定な同位体
- As-75
- 発見年
- 1250
存在度
- 存在度（地殻）
- 1.8 mg/kg 全元素の存在度（地殻）を比較 →
- 存在度（海洋）
- 3.7 mg/L 全元素の存在度（海洋）を比較 →
結晶構造
- 格子定数a
- 413 pm
電子構造
- 各電子殻の電子数
- 2, 8, 18, 5 全元素の各電子殻の電子数を比較 →
識別子
- CAS登録番号
- 7440-38-2 全元素のCAS登録番号を比較 →
- 項記号
- 4S°3/2
- InChI
- InChI=1S/As
- InChI Key
- RQNWIZPPADIBDY-UHFFFAOYSA-N
電子配置 測定値
As: 3d¹⁰ 4s² 4p³[Ar] 3d¹⁰ 4s² 4p³1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p³原子モデル
同位体によって中性子数、質量、安定性は変わりますが、中性原子の電子配置は変わりません。
模式的な原子モデルです。実際の縮尺とは異なります。
原子の指紋
発光／吸収スペクトル
同位体分布
| 質量数 | 原子質量（u） | 天然存在比 | 半減期 |
|---|---|---|---|
| 75 安定 | 74.92159457 ± 0.00000095 | 100.0000% | 安定 |
相／状態
理由: 昇華点（613.85 °C）より588.9 °C低い
模式図、実際の縮尺とは異なります
相転移点
相転移エネルギー
沸点で1 molを蒸発させるのに必要なエネルギー
昇華点で1 molを昇華させるのに必要なエネルギー
密度
標準条件下
標準条件下
詳細
原子スペクトル
全33件中10件を表示しています。 イオンの電荷の昇順で並べています。
スペクトル線データの収録状況 ?
| イオン | 電荷 | スペクトル線の総数 | 遷移確率 | 準位の表記 |
|---|---|---|---|---|
| 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 |
準位データの収録状況 ?
| イオン | 電荷 | 準位 |
|---|---|---|
| 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 |
イオン半径
| 電荷 | 配位 | スピン | 半径 |
|---|---|---|---|
| +3 | 6 | データなし | 57.99999999999999 pm |
| +5 | 4 | データなし | 33.5 pm |
| +5 | 6 | データなし | 46 pm |
化合物
同位体 (1)
| 質量数 | 原子質量（u） | 天然存在比 | 半減期 | 崩壊形式 | |
|---|---|---|---|---|---|
| 75 安定 | 74.92159457 ± 0.00000095 | 100.0000% | 安定 | stable |
詳細な性質
共有結合半径（詳細）
- 共有結合半径（Pyykkö）
- 121 pm
- 共有結合半径（Pyykkö、二重結合）
- 114 pm
- 共有結合半径（Pyykkö、三重結合）
- 106 pm
- 共有結合半径（Bragg）
- 126 pm
ファンデルワールス半径
- Bondi
- 185 pm
- Batsanov
- 205 pm
- Alvarez
- 188 pm
- UFF
- 423 pm
- MM3
- 236 pm
- Dreiding
- 415 pm
原子半径と金属半径
- 原子半径（Rahm）
- 231 pm
- 金属半径（C12）
- 148 pm
番号付けの尺度
- Mendeleev
- 95
- Pettifor
- 89
- Glawe
- 90
電気陰性度の尺度
- Ghosh
- 0
- Miedema
- 5
- Gunnarsson–Lundqvist
- 5
- Robles–Bartolotti
- 4
分極率と分散
- 双極子分極率
- 30 a.u.
- 双極子分極率（不確かさ）
- 1 a.u.
- C₆
- 246 Ha·Bohr6
- C₆ (Gould–Bučko)
- 260 Ha·Bohr6
ミーデマパラメータ
- ミーデマモル体積
- 11.85 cm3/mol
- ミーデマ電子密度
- 3
供給リスクと経済性
- 生産集中度
- 64
- 相対供給リスク
- 8
- 政治的安定性（最大生産国）
- 24
相転移と同素体
| 融点 | 1090.15 K |
| 沸点 | 889.15 K |
| 臨界点（温度） | 1673.15 K |
| 臨界点（圧力） | 22.3 MPa |
| 三重点（温度） | 1090.15 K |
| 三重点（圧力） | 3700 kPa |
酸化数の分類
専門参考データ
遮蔽定数 (8)
| n | 軌道 | 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 |
結晶半径の詳細 (3)
| 電荷 | CN | スピン | rcrystal (pm) | 由来 |
|---|---|---|---|---|
| 3 | VI | 72 | Ahrens (1952) ionic radius, | |
| 5 | IV | 47.5 | from r^3 vs V plots, | |
| 5 | VI | 60 | calculated, |
同位体の崩壊形式 (50)
| 同位体 | モード | 強度 |
|---|---|---|
| 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% |
X線散乱因子 (506)
| エネルギー (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 |
追加データ
Estimated Crustal Abundance
The estimated element abundance in the earth's crust.
1.8 milligrams per kilogram
参考文献 (1)
Estimated Oceanic Abundance
The estimated element abundance in the earth's oceans.
3.7-3 milligrams per liter
参考文献 (1)
参考文献
(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.