Cadmium (Cd)
transition-metalSolid
标准原子量
112.414 u电子排布
[Kr] 5s2 4d10熔点
321.07 °C沸点
766.85 °C密度
8690 kg/m³氧化态
−2, +1, +2电负性（鲍林）
1.69第一电离能
8.99382 eV发现年份
1817原子半径
155 pm详细信息
Cadmium is a soft, bluish-white post-transition metal in group 12. It occurs mainly as a minor constituent of zinc ores and is usually recovered as a by-product of zinc refining. Chemically it is dominated by the +2 oxidation state and forms many salts with ionic character. Its technological importance has declined in some applications because cadmium and many cadmium compounds are highly toxic, but it remains useful where particular electrochemical, pigment, or semiconductor properties are required.
Soft bluish metal belonging to group 12 of the periodic table. Extremely toxic even in low concentrations. Chemically similar to zinc, but lends itself to more complex compounds. Discovered in 1817 by F. Stromeyer.
The name derives from Greek kadmeia for "calamine" (zinc carbonate), with which it was found as an impurity in nature. It may have been found in furnace flue dust in Thebes, a city in the Boeottia region of central Greece. The mythological king of Phoenicia, Cadmus, founded Thebes and would be a source for the name of the ore. The element was discovered and first isolated by German physician Friedrich Stromeyer in 1817.
Cadmium was discovered by Friedrich Strohmeyer, a German chemist, in 1817 while studying samples of calamine (ZnCO3). When heated, Strohmeyer noticed that some samples of calamine glowed with a yellow color while other samples did not. After further examination, he determined that the calamine that changed color when heated contained trace amounts of a new element. There is only one mineral that contains significant amounts of cadmium, greenockite (CdS), but it is not common enough to mine profitably. Fortunately, small amounts of cadmium are found in zinc ores and most of the cadmium produced today is obtained as a byproduct of mining and refining zinc.
From the Latin word cadmia, Greek kadmeia - the ancient name for calamine, zinc carbonate. Discovered by Stromeyer in 1817 from an impurity in zinc carbonate. Cadmium most often occurs in small quantities associated with zinc ores, such as sphalerite (ZnS). Greenockite (CdS) is the only mineral of any consequence bearing cadmium. Almost all cadmium is obtained as a by-product in the treatment of zinc, copper, and lead ores. It is a soft, bluish-white metal which is easily cut with a knife. It is similar in many respects to zinc. In 1927 the International Conference on Weights and Measures redefined the meter in terms of the wavelength of the red cadmium spectral line (i.e. 1m = 1.553,164.13 wavelengths). This definition has been changed (see Krypton).
Pure cadmium is a silvery to bluish-white metal with a bright metallic luster when freshly cut. It is soft, malleable, and relatively low-melting for a structural metal. On exposure to air it slowly develops a dull surface film rather than remaining mirror-bright.
Cadmium metal has been used for corrosion-resistant electroplating on steel, especially where coatings must remain reliable in marine or aerospace service. Nickel-cadmium batteries use cadmium as the negative-electrode active material and remain important in some industrial and emergency applications, although many consumer uses have been replaced. Cadmium compounds are used in selected red, orange, and yellow pigments, in some plastics stabilizers of historical importance, and in cadmium telluride photovoltaic cells. Cadmium is also an efficient neutron absorber in control rods and shielding components.
Cadmium is a poisonous metal and its use is somewhat limited for this reason. Like zinc, cadmium can be electroplated to other materials to protect them from corrosion. Cadmium easily absorbs neutrons and is used to make control rods for nuclear reactors. Cadmium is also used in rechargeable nickel-cadmium batteries.
Cadmium is alloyed with silver to form solder, a metal with a relatively low melting point used to join electrical components, pipes and other metallic items. Cadmium based solders must be handled with care to prevent cadmium poisoning. Cadmium alloys are also used to make low friction bearings that are highly resistant to fatigue.
Hydrated cadmium sulfate (3CdSO4·5H2O), one of cadmium's compounds, is used in a device called a Weston cell, a type of battery that produces a precise voltage used to calibrate medical and laboratory equipment. Cadmium sulfide (CdS), another cadmium compound, is a yellow powder that is used as a pigment. Other cadmium compounds are used in the phosphors of black and white television sets and in the blue and green phosphors in color television sets.
Cadmium is a component of some of the lowest melting alloys; it is used in bearing alloys with low coefficients of friction and great resistance to fatigue; it is used extensively in electroplating, which accounts for about 60% of its use. It is also used in many types of solder, for standard E.M.F. cells, for Ni-Cd batteries, and as a barrier to control nuclear fission. Cadmium compounds are used in black and white television phosphors and in blue and green phosphors for color TV tubes. It forms a number of salts, of which the sulfate is most common; the sulfide is used as a yellow pigment. Cadmium and solutions of its compounds are toxic.
Isotopes in Biology
Metal accumulation is a threat to our world’s water systems and wildlife. As a way to measure the influence of heavy metals on wildlife utilizing mass spectrometric techniques, some researchers use animal food enriched in specific cadmium isotopes. These experiments work by exposing the animals to a diet enriched in 106Cd and/or other stable isotopes of metals (for example, 65Cu and/or 62Ni) for a period of time. Depending on the purpose of the experiment, the residence time of the food in the gut is determined and isotopic compositions of the gut and/or feces are measured viainductively coupled plasma mass spectrometry (ICP-MS). This information is used to measure bio-uptake (absorption and incorporation of a substance by living tissue) and accumulation rates of metals in an exposed animal [355] M. N. Croteau, S. N. Luoma, B. Pellet. Aquat. Toxicol.83, 116 (2007)., [356] M. N. Croteau, S. N. Luoma. Environ. Sci. Technol.43, 4915 (2009)..
Isotopes in Earth/Planetary Science
Molecules, atoms, and ions of the stable isotopes of cadmium possess slightly different physical and chemical properties, and they commonly will be fractionated during physical, chemical, and biological processes, giving rise to variations in isotopic abundances and in atomic weights. There are small but measureable variations in the isotopic abundances of dissolved cadmium in ocean water, which are a consequence of isotopic fractionation associated with biological uptake (Fig. IUPAC.48.1) [357] F. Lacan, R. Francois, Y. Ji, R. M. Sherrell. Geochim. Cosmochim. Acta70, 5104 (2006)., [358] W. Abouchami, S. J. G. Galer, H. J. W. d. Baar, A. C. Alderkamp, R. Middag, P. Laan, H. Feldmann, M. O. Andreae. Earth. Planet. Sci. Lett.305, 83 (2011)., [359] Z. Xue, M. Rehkämper, T. J. Horner, W. Abouchami, R. Middag, T. v. d. Flierd, H. J. W. d. Baar. Earth. Planet. Sci. Lett.382, 161 (2013)..
Isotopes Used as a Source of Radioactive Isotope(s)
112Cd is used to produce the diagnostic radioisotope 111In (with a half-life of 2.8 days) via the reaction 112Cd (p, 2n) 111In [94] International Atomic Energy Agency. Cyclotron Produced Radionuclides: Physical Characteristics and Production Methods, Technical Reports Series No. 468. International Atomic Energy Agency Vienna (2009)..
Cadmium chemistry is centered on Cd²⁺; the +1 state is uncommon and usually involves metal-metal bonded species rather than simple stable salts. Cadmium sulfide, CdS, is a yellow semiconductor and pigment, while cadmium selenide, CdSe, and cadmium telluride, CdTe, are important semiconducting materials. Cadmium oxide, CdO, is a brown to black oxide used in some electronic and plating-related applications. Soluble salts such as cadmium chloride, CdCl₂, and cadmium nitrate, Cd(NO₃)₂, are important laboratory or industrial intermediates but are especially hazardous because they make Cd²⁺ readily bioavailable.
See more information at the Cadmium compound page.
Cadmium metal dust, fumes, and soluble cadmium salts are highly toxic. Inhalation of cadmium oxide, CdO, fumes from heating or welding cadmium-containing materials can cause severe acute lung injury. Chronic exposure can damage kidneys and bones, and cadmium compounds are recognized human carcinogens in occupational settings. Cadmium has no known essential biological role, and exposure control is central to its handling.
Failure to appreciate the toxic properties of cadmium may cause workers to be unwittingly exposed to dangerous fumes. Silver solder, for example, which contains cadmium, should be handled with care. Serious toxicity problems have been found from long-term exposure and work with cadmium plating baths. Exposure to cadmium dust should not exceed 0.01 mg/m3 (8-hour time-weighted average, 40-hour week). The ceiling concentration (maximum), for a period of 15 min, should not exceed 0.14 mg/m3. Cadmium oxide fume exposure (8-hour, 40-hour week) should not exceed 0.05 mg/m3, and the maximum concentration should not exceed 0.05 mg/m3. These values are presently being restudied and recommendations have been made to reduce the exposure.
Cadmium is a naturally occurring trace element released by weathering, volcanism, and the processing or combustion of mineral materials. It is relatively mobile under acidic conditions and can accumulate in soils and sediments. Plants can take up Cd²⁺ from contaminated soil, allowing entry into food chains, especially near smelters, phosphate fertilizers, or waste sites. In aquatic systems, sulfide-rich sediments can immobilize cadmium as poorly soluble sulfides.
Cadmium supply is tied closely to zinc production because most recoverable cadmium is obtained from flue dusts, residues, and electrolytic refining streams during zinc processing. Demand has contracted in many regions as restrictions and substitution reduced uses in pigments, stabilizers, and consumer batteries. Remaining demand is concentrated in industrial nickel-cadmium batteries, specialized coatings, semiconductors, and control materials. Recycling is important for batteries and some industrial scrap, both to recover material and to keep cadmium out of general waste streams. There is no large independent cadmium mining industry comparable to major base metals.
Obtained as a by product of zinc refining.
Cadmium is a relatively rare element in the cosmos. Its stable isotopes are produced mainly by slow and rapid neutron-capture processes in earlier generations of stars, followed by dispersal into interstellar material. In planets it behaves as a chalcophile and moderately volatile element, so it tends to associate with sulfide phases and can be depleted from high-temperature condensed materials.
- Cadmium was identified in the early 19th century as an impurity in zinc compounds.
- Cadmium plating offers good sacrificial protection but is now tightly restricted in many applications.
- Cadmium yellow pigment is based largely on cadmium sulfide, CdS.
- Natural cadmium consists of several stable isotopes and a few very long-lived radioisotopes.
- Cadmium can form low-melting alloys used in some fusible safety devices.
- Rice and leafy vegetables can be significant dietary cadmium sources in contaminated areas.
图片
性质
物理性质
- 原子半径（经验值）
- 155 pm 比较所有元素的原子半径（经验值） →
- 共价半径
- 144 pm 比较所有元素的共价半径 →
- 范德华半径
- 158 pm 比较所有元素的范德华半径 →
- 金属半径
- 138 pm 比较所有元素的金属半径 →
- 密度
- 8690 kg/m³ 比较所有元素的密度 →
- 摩尔体积
- 0.0131 L/mol
- 标准温度和压力下的物相
- 固态 比较所有元素的标准温度和压力下的物相 →
- 熔点
- 321.07 °C 比较所有元素的熔点 →
- 沸点
- 766.85 °C 比较所有元素的沸点 →
- 热导率
- 96.9 W/(m·K) 比较所有元素的热导率 →
- 比热容
- 0.232 J/(g·K) 比较所有元素的比热容 →
- 摩尔热容
- 26.02 J/(mol·K) 比较所有元素的摩尔热容 →
- 晶体结构
- 六方密堆积 比较所有元素的晶体结构 →
化学性质
- 电负性（鲍林）
- 1.69 比较所有元素的电负性（鲍林） →
- 电负性（Allen）
- 1.52
- 电子亲和能
- -0.7 eV (负值——预计该原子不结合额外电子)
- 第一电离能
- 8.99382 eV 比较所有元素的第一电离能 →
- 第二电离能
- 16.908371 eV 比较所有元素的第二电离能 →
- 第三电离能
- 37.468129 eV 比较所有元素的第三电离能 →
- 第四电离能
- 51.000176 eV 比较所有元素的第四电离能 →
- 第五电离能
- 67.900234 eV 比较所有元素的第五电离能 →
- 氧化态
- −2, +1, +2 比较所有元素的氧化态 →
- 价电子
- 12 比较所有元素的价电子 →
- 电子排布
- [Kr] 5s2 4d10
热力学性质
- 熔化热
- 0.06436234 eV 比较所有元素的熔化热 →
- 汽化热
- 1.036431 eV 比较所有元素的汽化热 →
- 升华热
- 1.160802 eV
- 原子化热
- 1.160802 eV
- 原子化焓
- 1.158729 eV
核性质
- 质子
- 48 比较所有元素的质子 →
- 中子
- 64 比较所有元素的中子 →
- 已知同位素
- 42 比较所有元素的已知同位素 →
- 稳定同位素
- 3 比较所有元素的稳定同位素 →
- 最稳定同位素
- Cd-112
- 发现年份
- 1817
丰度
- 丰度（地壳）
- 0.15 mg/kg 比较所有元素的丰度（地壳） →
- 丰度（海洋）
- 1.1 × 10−4 mg/L 比较所有元素的丰度（海洋） →
晶体结构
- 晶格常数a
- 298 pm
电子结构
- 各电子层电子数
- 2, 8, 18, 18, 2 比较所有元素的各电子层电子数 →
标识符
- CAS登记号
- 7440-43-9 比较所有元素的CAS登记号 →
- 谱项符号
- 1S0
- InChI
- InChI=1S/Cd
- InChI Key
- BDOSMKKIYDKNTQ-UHFFFAOYSA-N
电子排布 实测值
Cd: 4d¹⁰ 5s²[Kr] 4d¹⁰ 5s²1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 5s²原子模型
不同同位素的中子数、质量和稳定性不同，但中性原子的电子排布不变。
原子模型示意图，未按比例绘制。
原子指纹
发射 / 吸收光谱
同位素分布
| 质量数 | 原子质量（u） | 天然丰度 | 半衰期 |
|---|---|---|---|
| 110 稳定 | 109.90300661 ± 0.00000061 | 12.4900% | 稳定 |
| 111 稳定 | 110.90418287 ± 0.00000061 | 12.8000% | 稳定 |
| 112 稳定 | 111.90276287 ± 0.0000006 | 24.1300% | 稳定 |
物相 / 状态
原因: 低于熔点（321.07 °C）296.1 °C
示意图，未按比例绘制
相变点
相变能
在熔点熔化1 mol物质所需的能量
在沸点汽化1 mol物质所需的能量
在升华点升华1 mol物质所需的能量
密度
标准条件下
标准条件下
原子光谱
已显示10项，共48项。 按离子电荷升序排列。
收录能级 ?
| 离子 | 电荷 | 能级 |
|---|---|---|
| Cd I | 0 | 128 |
| Cd II | +1 | 101 |
| Cd III | +2 | 48 |
| Cd IV | +3 | 52 |
| Cd V | +4 | 2 |
| Cd VI | +5 | 2 |
| Cd VII | +6 | 2 |
| Cd VIII | +7 | 2 |
| Cd IX | +8 | 2 |
| Cd X | +9 | 2 |
离子半径
| 电荷 | 配位 | 自旋 | 半径 |
|---|---|---|---|
| +2 | 4 | 暂无 | 78 pm |
| +2 | 5 | 暂无 | 87 pm |
| +2 | 6 | 暂无 | 95 pm |
| +2 | 7 | 暂无 | 103 pm |
| +2 | 8 | 暂无 | 110.00000000000001 pm |
| +2 | 12 | 暂无 | 131 pm |
化合物
同位素 (3)
| 质量数 | 原子质量（u） | 天然丰度 | 半衰期 | 衰变方式 | |
|---|---|---|---|---|---|
| 110 稳定 | 109.90300661 ± 0.00000061 | 12.4900% ± 0.1800% | 稳定 | stable | |
| 111 稳定 | 110.90418287 ± 0.00000061 | 12.8000% ± 0.1200% | 稳定 | stable | |
| 112 稳定 | 111.90276287 ± 0.0000006 | 24.1300% ± 0.2100% | 稳定 | stable |
谱线
| 波长（nm） | 强度 | 电离级 | 类型 | 跃迁 | 准确度 | 来源 | |
|---|---|---|---|---|---|---|---|
| 398.19257 nm | 10 | Cd I | emission | 4d10.5s.5p 1P* → 4d10.5s.9s 1S | 实测值 | NIST | |
| 414.03021 nm | 暂无 | Cd I | emission | 4d10.5s.5p 1P* → 4d10.5s.7d 1D | 实测值 | NIST | |
| 430.66718 nm | 8 | Cd I | emission | 4d10.5s.5p 1P* → 4d10.5s.8s 1S | 实测值 | NIST | |
| 441.29894 nm | 3 | Cd I | emission | 4d10.5s.5p 3P* → 4d10.5s.6s 1S | 实测值 | NIST | |
| 466.2352 nm | 8 | Cd I | emission | 4d10.5s.5p 1P* → 4d10.5s.6d 1D | 实测值 | NIST | |
| 467.815 nm | 200 | Cd I | emission | 4d10.5s.5p 3P* → 4d10.5s.6s 3S | 实测值 | NIST | |
| 479.99121 nm | 300 | Cd I | emission | 4d10.5s.5p 3P* → 4d10.5s.6s 3S | 实测值 | NIST | |
| 508.58214 nm | 暂无 | Cd I | emission | 4d10.5s.5p 3P* → 4d10.5s.6s 3S | 实测值 | NIST | |
| 515.46618 nm | 6 | Cd I | emission | 4d10.5s.5p 1P* → 4d10.5s.7s 1S | 实测值 | NIST | |
| 609.9142 nm | 300 | Cd I | emission | 4d10.5s.6s 3S → 4d10.5s.8p 3P* | 实测值 | NIST | |
| 611.1495 nm | 100 | Cd I | emission | 4d10.5s.6s 3S → 4d10.5s.8p 3P* | 实测值 | NIST | |
| 632.51689 nm | 100 | Cd I | emission | 4d10.5s.5p 1P* → 4d10.5s.5d 3D | 实测值 | NIST | |
| 633.00149 nm | 30 | Cd I | emission | 4d10.5s.5p 1P* → 4d10.5s.5d 3D | 实测值 | NIST | |
| 643.84695 nm | 2000 | Cd I | emission | 4d10.5s.5p 1P* → 4d10.5s.5d 1D | 实测值 | NIST | |
| 677.8116 nm | 30 | Cd I | emission | 4d10.5s.6s 1S → 4d10.5s.8p 1P* | 实测值 | NIST | |
| 734.5665 nm | 1000 | Cd I | emission | 4d10.5s.6s 3S → 4d10.5s.7p 3P* | 实测值 | NIST |
扩展性质
共价半径（扩展）
- 共价半径（Pyykkö）
- 136 pm
- 共价半径（Pyykkö，双键）
- 144 pm
- 共价半径（Bragg）
- 160 pm
范德华半径
- Batsanov
- 220 pm
- Alvarez
- 249 pm
- UFF
- 284.8 pm
- MM3
- 250 pm
原子半径与金属半径
- 原子半径（Rahm）
- 238 pm
- 金属半径（C12）
- 151 pm
编号标度
- Mendeleev
- 78
- Pettifor
- 75
- Glawe
- 75
电负性标度
- Ghosh
- 0
- Miedema
- 4
- Gunnarsson–Lundqvist
- 4
- Robles–Bartolotti
- 3
极化率与色散
- 偶极极化率
- 46 a.u.
- 偶极极化率（不确定度）
- 2 a.u.
- C₆ (Gould–Bučko)
- 405 Ha·Bohr6
Miedema参数
- Miedema摩尔体积
- 13 cm3/mol
- Miedema电子密度
- 2
供应风险与经济性
- 生产集中度
- 32
- 相对供应风险
- 7
- 储量分布
- 20
- 政治稳定性（最大生产国）
- 24
- 政治稳定性（最大储量国）
- 11
相变与同素异形体
| 熔点 | 594.22 K |
| 沸点 | 1040.15 K |
氧化态分类
高级参考数据
屏蔽常数 (10)
| n | 轨道 | σ |
|---|---|---|
| 1 | s | 0.9744 |
| 2 | p | 4.091 |
| 2 | s | 12.6142 |
| 3 | d | 14.3931 |
| 3 | p | 17.3085 |
| 3 | s | 17.1588 |
| 4 | d | 32.1232 |
| 4 | p | 28.5888 |
| 4 | s | 27.1308 |
| 5 | s | 39.808 |
晶体半径详情 (6)
| 电荷 | CN | 自旋 | rcrystal (pm) | 来源 |
|---|---|---|---|---|
| 2 | IV | 92 | ||
| 2 | V | 101 | ||
| 2 | VI | 109 | ||
| 2 | VII | 117 | calculated, | |
| 2 | VIII | 124 | calculated, | |
| 2 | XII | 145 |
同位素衰变方式 (59)
| 同位素 | 模式 | 强度 |
|---|---|---|
| 94 | B+ | — |
| 94 | B+p | — |
| 95 | B+ | 100% |
| 95 | B+p | 4.6% |
| 96 | B+ | 100% |
| 96 | B+p | 1.6% |
| 97 | B+ | 100% |
| 97 | B+p | 7.4% |
| 98 | B+ | 100% |
| 98 | B+p | 0% |
X射线散射因子 (510)
| 能量 (eV) | f₁ | f₂ |
|---|---|---|
| 10 | — | 0.40004 |
| 10.1617 | — | 0.41842 |
| 10.3261 | — | 0.43764 |
| 10.4931 | — | 0.45775 |
| 10.6628 | — | 0.49362 |
| 10.8353 | — | 0.53685 |
| 11.0106 | — | 0.59258 |
| 11.1886 | — | 0.66328 |
| 11.3696 | — | 0.74242 |
| 11.5535 | — | 0.86125 |
补充数据
Estimated Crustal Abundance
The estimated element abundance in the earth's crust.
1.5×10-1 milligrams per kilogram
参考文献 (1)
Estimated Oceanic Abundance
The estimated element abundance in the earth's oceans.
1.1×10-4 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 Cadmium.
The element property data was retrieved from publications.