Actinium (Ac)
actinideSolid
标准原子量
[227]电子排布
[Rn] 7s2 6d1熔点
1050.85 °C沸点
3197.85 °C密度
1.007e+4 kg/m³氧化态
+3电负性（鲍林）
1.1第一电离能
5.380235 eV发现年份
1899原子半径
195 pm详细信息
Actinium is a radioactive actinide metal and the element that gives the actinide series its name. Natural actinium is present only in minute amounts, chiefly as ²²⁷Ac in uranium decay chains. Its chemistry is dominated by the +3 oxidation state and resembles that of lanthanum more than the later, more strongly 5f-influenced actinides. Because all isotopes are radioactive and scarce, most knowledge comes from tracer-scale chemistry rather than ordinary bulk handling.
Actinium-227, a decay product of uranium-235, is a beta emitter with a 21.6-year half-life. Its principal decay products are thorium-227 (18.5-day half-life), radium-223 (11.4-day half-life), and a number of short-lived products including radon, bismuth, polonium, and lead isotopes. In equilibrium with its decay products, it is a powerful source of alpha particles. Actinium metal has been prepared by the reduction of actinium fluoride with lithium vapor at about 1100 to 1300-degrees C. The chemical behavior of actinium is similar to that of the rare earths, particularly lanthanum. Purified actinium comes into equilibrium with its decay products at the end of 185 days, and then decays according to its 21.6-year half-life. It is about 150 times as active as radium, making it of value in the production of neutrons.
In April of 2012, Los Alamos National Laboratory announced a new medical isotope project that shows promise for rapidly producing major quantities of a new cancer-treatment agent, actinium 225 (Ac-225). Both a press release and a video are available.
Actinium was discovered in 1899 by André-Louis Debierne, a French chemist, while experimenting with new methods of separating rare earth oxides. Friedrich Otto Giesel independently discovered actinium in 1902. Actinium is a rare element that is present in uranium ores in tiny amounts, but it is usually cheaper and easier to create actinium when it is needed by bombarding radium with neutrons in a nuclear reactor.
Actinium's most stable isotope, actinium-227, has a half-life of 21.77 years. It decays into francium-223 through alpha decay or into thorium-227 through beta decay.
From the Greek aktis, aktinos, meaning beam or ray. Discovered by Andre Debierne in 1899 and independently by F. Giesel in 1902. Occurs naturally in association with uranium minerals.
A freshly prepared macroscopic sample has rarely been available. Metallic actinium is described as silvery, but its bulk appearance and many physical properties are not as well characterized as those of common metals. It is expected to tarnish rapidly in air and to be self-luminous in the dark from intense radioactivity exciting surrounding materials.
Actinium has no broad commercial use as an elemental material. ²²⁵Ac is important in research and limited clinical development for targeted alpha therapy, where it is attached to carrier molecules intended to deliver alpha-emitting decay products to diseased cells. ²²⁷Ac has been used as a source for generating ²²⁷Th and other decay-chain nuclides, and actinium isotopes are used in radiochemical research, detector calibration, and studies of actinide separation chemistry. Proposed neutron-source uses with light-element targets are historically noted but are not a major present application.
Actinium has no significant commercial applications, although it is used in the production of neutrons.
Isotopes in Earth/Planetary Science
227Ac (with a half-life of 21.77 years) has been used as a tracer of deep-sea mixing in the oceans. By determining concentrations of 227Ac in a water column, scientists can study the rates and patterns of mixing and other vertical exchange processes [583] W. Geibert, M. M. Rutgers van der Loeff, C. Hanfland, H. J. Dauelsberg. Earth. Planet. Sci. Lett.198, 147 (2002).. As a product of the 235U decay chain, 227Ac and other radioisotopes have been used to determine information about the movement of fluids in mid-oceanic ridges and basaltic melts [584] D. McKenzie. Chem. Geol.162, 81 (2000)., [585] W. S. Moore, W. Ussler III, C. K. Paull. Mar. Chem.109, 421 (2008)..
Isotopes in Medicine
225Ac (with a half-life of 10 days) can be used in cancer treatments (Fig. IUPAC.89.1). The isotope is attached to a chelating agent (a substance that can form multiple bonds to a single metal ion) and delivered to the problem site. The emissions of alpha particles from actinium and its daughter products cause tumor death [586] M. R. McDevitt, D. Ma, L. T. Lai, J. Simon, P. Borchardt, R. K. Frank, K. Wu, V. Pellegrini, M. J. Curcio, M. Miederer, N. H. Bander, D. A. Scheinberg. Science294, 1537 (2001).. 225Ac in a series of alpha decays produces 213Bi (with a half-life of 0.76 h), which is also used for radioimmunotherapy [587] D. Ma, M. R. McDevitt, R. D. Finn, D. A. Scheinberg. Appl. Radiat. Isot.55, 667 (2001)..
Isotopes Used as a Source of Radioactive Isotope(s)
225Ac, which is a pure alpha emitter, is used to produce 213Bi with an 225Ac/ 213Bi radionuclide generator (Fig. IUPAC.89.2). 213Bi is a mixed alpha and beta emitter. The primary mode of decay is by beta emission to the very short-lived, alpha emitter 213Po. The 8.4 MeV alpha particle emitted by 213Po has a path length of 76 μm in human tissue and is responsible for its cytotoxic effects.
Actinium chemistry is almost entirely trivalent, with Ac³⁺ forming colorless or pale salts in the absence of colored counterions. Representative compounds include actinium oxide, Ac₂O₃, actinium fluoride, AcF₃, actinium chloride, AcCl₃, and actinium hydroxide, Ac(OH)₃. The ion is large and hard, so it favors oxygen- and fluorine-donor ligands and forms sparingly soluble fluorides, phosphates, oxalates, and hydroxides. Higher oxidation states are not established for ordinary actinium chemistry.
See more information at the Actinium compound page.
All actinium isotopes are radioactive, and safety depends strongly on isotope, activity, chemical form, and route of exposure. ²²⁷Ac is long-lived enough to persist and produces a chain of radioactive daughters, while ²²⁵Ac is a potent alpha emitter used only under controlled radiochemical conditions. Internal uptake is the principal concern because alpha particles cause severe local ionization in tissue. External gamma radiation from daughter products can also require shielding and remote handling.
Natural actinium occurs at trace levels in uranium-bearing minerals as part of decay chains and is continuously formed and lost by radioactive decay. In the environment Ac³⁺ is expected to bind strongly to mineral surfaces, organic matter, and phosphate- or carbonate-containing solids, limiting mobility under many conditions. It has no known biological role. Releases outside specialized nuclear or radiochemical settings are uncommon, and environmental behavior is inferred largely from tracer studies and analog chemistry.
Actinium is not traded as a bulk commodity. Usable quantities are obtained by radiochemical separation from decay products or by accelerator and reactor routes, depending on the isotope required. ²²⁵Ac supply is especially constrained because it must be isolated from suitable parent nuclides or produced by irradiation, followed by difficult purification from chemically similar actinides and radioactive daughters. Costs and availability are therefore governed by nuclear infrastructure, isotope purity, licensing, and short logistical timelines rather than mining demand. Recycling is mainly recovery from radiochemical processing streams.
Extremely rare, found in all uranium ores. Usually obtained by treating radium with neutrons in a reactor.
Actinium has no stable isotopes, so any primordial actinium has long since decayed. In nature and in planetary materials it exists only as a transient member of heavy-element decay chains, especially those derived from uranium and thorium. The heavy nuclei that ultimately feed these chains were produced by neutron-capture processes in earlier stellar events, but actinium itself is not a significant cosmic reservoir.
- Actinium was discovered through its radioactivity before its chemistry could be studied in ordinary amounts.
- The name comes from the Greek word for a ray or beam.
- ²²⁷Ac is a decay product in the ²³⁵U series.
- The element is usually handled at tracer scale, where carrier chemistry is often needed.
- Ac³⁺ is among the largest tripositive actinide ions.
- Separating actinium from lanthanum is chemically difficult because their ionic behavior is similar.
图片
性质
物理性质
- 原子半径（经验值）
- 195 pm 比较所有元素的原子半径（经验值） →
- 共价半径
- 215 pm 比较所有元素的共价半径 →
- 范德华半径
- 260 pm 比较所有元素的范德华半径 →
- 密度
- 1.007 × 104 kg/m³ 比较所有元素的密度 →
- 摩尔体积
- 0.02254 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
- 1050.85 °C 比较所有元素的熔点 →
- 沸点
- 3197.85 °C 比较所有元素的沸点 →
- 比热容
- 0.12 J/(g·K) 比较所有元素的比热容 →
- 摩尔热容
- 27.2 J/(mol·K) 比较所有元素的摩尔热容 →
- 晶体结构
- 面心立方 比较所有元素的晶体结构 →
化学性质
- 电负性（鲍林）
- 1.1 比较所有元素的电负性（鲍林） →
- 电子亲和能
- 0.35 eV
- 第一电离能
- 5.380235 eV 比较所有元素的第一电离能 →
- 第二电离能
- 11.75004 eV 比较所有元素的第二电离能 →
- 第三电离能
- 17.43606 eV 比较所有元素的第三电离能 →
- 第四电离能
- 44.800154 eV 比较所有元素的第四电离能 →
- 第五电离能
- 55.000189 eV 比较所有元素的第五电离能 →
- 氧化态
- +3 比较所有元素的氧化态 →
- 价电子
- 3 比较所有元素的价电子 →
- 电子排布
- [Rn] 7s2 6d1
热力学性质
- 熔化热
- 0.14510027 eV 比较所有元素的熔化热 →
- 汽化热
- 4.145722 eV 比较所有元素的汽化热 →
- 升华热
- 4.456651 eV
- 原子化热
- 4.456651 eV
- 原子化焓
- 4.207908 eV
核性质
- 质子
- 89 比较所有元素的质子 →
- 中子
- 138 比较所有元素的中子 →
- 已知同位素
- 33 比较所有元素的已知同位素 →
- 稳定同位素
- 0 比较所有元素的稳定同位素 →
- 质量数（最稳定同位素）
- 227
- 最稳定同位素
- Ac-227
- 发现年份
- 1899
丰度
- 丰度（地壳）
- 5.5e-10 mg/kg 比较所有元素的丰度（地壳） →
晶体结构
- 晶格常数a
- 531 pm
电子结构
- 各电子层电子数
- 2, 8, 18, 32, 18, 9, 2 比较所有元素的各电子层电子数 →
标识符
- CAS登记号
- 7440-34-8 比较所有元素的CAS登记号 →
- 谱项符号
- 2D3/2
- InChI
- InChI=1S/Ac
- InChI Key
- QQINRWTZWGJFDB-UHFFFAOYSA-N
电子排布 实测值
Ac: 6d¹ 7s²[Rn] 6d¹ 7s²1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 5s² 5p⁶ 4f¹⁴ 5d¹⁰ 6s² 6p⁶ 6d¹ 7s²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
无稳定同位素。
| 质量数 | 原子质量（u） | 天然丰度 | 半衰期 |
|---|---|---|---|
| 212 放射性 | 212.007813 ± 0.000055 | 暂无 | 895 ms |
| 213 放射性 | 213.006609 ± 0.000056 | 暂无 | 738 ms |
| 216 放射性 | 216.008743 ± 0.000012 | 暂无 | 440 us |
| 210 放射性 | 210.009436 ± 0.000062 | 暂无 | 350 ms |
| 211 放射性 | 211.007732 ± 0.000057 | 暂无 | 213 ms |
物相 / 状态
原因: 低于熔点（1050.85 °C）1025.8 °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89项。 按离子电荷升序排列。
收录能级 ?
| 离子 | 电荷 | 能级 |
|---|---|---|
| Ac I | 0 | 53 |
| Ac II | +1 | 84 |
| Ac III | +2 | 8 |
| Ac IV | +3 | 2 |
| Ac V | +4 | 2 |
| Ac VI | +5 | 2 |
| Ac VII | +6 | 2 |
| Ac VIII | +7 | 2 |
| Ac IX | +8 | 2 |
| Ac X | +9 | 2 |
离子半径
| 电荷 | 配位 | 自旋 | 半径 |
|---|---|---|---|
| +3 | 6 | 暂无 | 112.00000000000001 pm |
| +3 | 9 | 暂无 | 122 pm |
化合物
同位素 (5)
| 质量数 | 原子质量（u） | 天然丰度 | 半衰期 | 衰变方式 | |
|---|---|---|---|---|---|
| 212 放射性 | 212.007813 ± 0.000055 | 暂无 | 895 ms | α ≈100%β+ ? | |
| 213 放射性 | 213.006609 ± 0.000056 | 暂无 | 738 ms | α ≈100%β+ ? | |
| 216 放射性 | 216.008743 ± 0.000012 | 暂无 | 440 us | α =100%β+ ? | |
| 210 放射性 | 210.009436 ± 0.000062 | 暂无 | 350 ms | α ≈100%β+ ? | |
| 211 放射性 | 211.007732 ± 0.000057 | 暂无 | 213 ms | α ≈100%β+ ? |
谱线
已显示50项，共213项。 默认仅显示具有实测强度的谱线。
| 波长（nm） | 强度 | 电离级 | 类型 | 跃迁 | 准确度 | 来源 | |
|---|---|---|---|---|---|---|---|
| 391.4468 nm | 24000 | Ac II | emission | 6d.7s 3D → 5f.7s 3F* | 实测值 | NIST | |
| 417.99772 nm | 17000 | Ac I | emission | 6d.7s2 2D → 6d.7s.(1D).7p 2D* | 实测值 | NIST | |
| 481.2218 nm | 16000 | Ac II | emission | 6d.7s 3D → 7s.7p 3P* | 实测值 | NIST | |
| 438.64 nm | 15000 | Ac II | emission | 6d.7s 1D → 6d.7p 1D* | 实测值 | NIST | |
| 397.736 nm | 13000 | Ac II | emission | 6d2 3F → 6d.7p 3P* | 实测值 | NIST | |
| 445.2188 nm | 12000 | Ac II | emission | 6d.7s 3D → 6d.7p 3F* | 实测值 | NIST | |
| 388.55592 nm | 9000 | Ac I | emission | 6d.7s2 2D → 6d.7s.(3D).7p 2P* | 实测值 | NIST | |
| 401.9622 nm | 8700 | Ac II | emission | 6d2 3F → 5f.6d 1G* | 实测值 | NIST | |
| 544.6367 nm | 8700 | Ac II | emission | 6d2 3F → 6d.7p 3D* | 实测值 | NIST | |
| 435.9118 nm | 7300 | Ac II | emission | 6d.7s 3D → 7s.7p 3P* | 实测值 | NIST | |
| 446.27307 nm | 6900 | Ac I | emission | 6d.7s2 2D → 6d.7s.(1D).7p 2F* | 实测值 | NIST | |
| 471.65807 nm | 6900 | Ac I | emission | 6d.7s2 2D → 6d.7s.(1D).7p 2F* | 实测值 | NIST | |
| 495.8233 nm | 6800 | Ac II | emission | 6d.7s 1D → 6d.7p 1P* | 实测值 | NIST | |
| 384.304 nm | 6600 | Ac I | emission | 6d.7s2 2D → 6d.7s.(3D).7p 2P* | 实测值 | NIST | |
| 392.0101 nm | 6500 | Ac II | emission | 6d2 3P → 5f.6d 1D* | 实测值 | NIST | |
| 418.31199 nm | 6400 | Ac I | emission | 6d.7s2 2D → 6d.7s.(3D).7p 2F* | 实测值 | NIST | |
| 439.67158 nm | 5800 | Ac I | emission | 6d.7s2 2D → 6d.7s.(3D).7p 2F* | 实测值 | NIST | |
| 419.43971 nm | 5300 | Ac I | emission | 6d.7s2 2D → 6d.7s.(1D).7p 2P* | 实测值 | NIST | |
| 494.5181 nm | 5300 | Ac II | emission | 6d2 3F → 6d.7p 3D* | 实测值 | NIST | |
| 496.0869 nm | 4900 | Ac II | emission | 6d2 3F → 6d.7p 3D* | 实测值 | NIST | |
| 461.39285 nm | 4000 | Ac I | emission | 6d.7s2 2D → 6d.7s.(3D).7p 2F* | 实测值 | NIST | |
| 527.15603 nm | 3800 | Ac I | emission | 6d.7s2 2D → 6d.7s.(1D).7p 2F* | 实测值 | NIST | |
| 406.31064 nm | 3700 | Ac I | emission | 6d.7s2 2D → 6d.7s.(1D).7p 2D* | 实测值 | NIST | |
| 407.8693 nm | 3700 | Ac II | emission | 6d.7s 3D → 6d.7p 1P* | 实测值 | NIST | |
| 403.4629 nm | 3500 | Ac I | emission | 6d.7s2 2D → 6d2.(3F).7p 4G* | 实测值 | NIST | |
| 420.9682 nm | 3500 | Ac II | emission | 6d.7s 3D → 5f.7s 1F* | 实测值 | NIST | |
| 669.5231 nm | 3300 | Ac II | emission | 6d2 3F → 6d.7p 3F* | 实测值 | NIST | |
| 474.0522 nm | 2600 | Ac II | emission | 6d2 1G → 6d.7p 1F* | 实测值 | NIST | |
| 515.6541 nm | 2100 | Ac II | emission | 6d2 3F → 5f.7s 3F* | 实测值 | NIST | |
| 383.53206 nm | 1900 | Ac I | emission | 6d.7s2 2D → 6d.7s.(1D).7p 2P* | 实测值 | NIST | |
| 488.9102 nm | 1800 | Ac II | emission | 6d2 3F → 5f.7s 3F* | 实测值 | NIST | |
| 480.7843 nm | 1700 | Ac II | emission | 6d.7s 1D → 6d.7p 3F* | 实测值 | NIST | |
| 534.47384 nm | 1700 | Ac I | emission | 6d2.(3F).7s 4F → 6d2.(3F).7p 4G* | 实测值 | NIST | |
| 400.5469 nm | 1500 | Ac II | emission | 6d2 1G → 5f.6d 3G* | 实测值 | NIST | |
| 536.2615 nm | 1400 | Ac II | emission | 6d2 3F → 6d.7p 1D* | 实测值 | NIST | |
| 522.8309 nm | 1300 | Ac I | emission | 6d.7s2 2D → 6d.7s.(3D).7p 4D* | 实测值 | NIST | |
| 454.408 nm | 1200 | Ac II | emission | 6d2 1D → 7s.7p 1P* | 实测值 | NIST | |
| 461.01055 nm | 1100 | Ac I | emission | 6d.7s2 2D → 6d.7s.(1D).7p 2D* | 实测值 | NIST | |
| 422.599 nm | 1000 | Ac I | emission | 6d2.(3F).7s 4F → 6d2.(3F).7p 4D* | 实测值 | NIST | |
| 387.7035 nm | 980 | Ac II | emission | 6d.7p 3P* → 5f.7p 3D | 实测值 | NIST | |
| 420.89072 nm | 960 | Ac I | emission | 6d2.(3F).7s 4F → 6d2.(3F).7p 4D* | 实测值 | NIST | |
| 469.05284 nm | 960 | Ac I | emission | 6d2.(3F).7s 4F → 6d2.(3F).7p 4F* | 实测值 | NIST | |
| 521.5399 nm | 960 | Ac II | emission | 6d2 3P → 6d.7p 3P* | 实测值 | NIST | |
| 486.88523 nm | 890 | Ac I | emission | 6d2.(3F).7s 4F → 6d2.(3F).7p 4F* | 实测值 | NIST | |
| 526.4481 nm | 890 | Ac I | emission | 7s2.7p 2P* → 7s2.8s 2S | 实测值 | NIST | |
| 440.21056 nm | 860 | Ac I | emission | 6d2.(3F).7s 4F → 6d2.(3F).7p 4F* | 实测值 | NIST | |
| 447.18106 nm | 850 | Ac I | emission | 6d2.(3F).7s 4F → 6d2.(3F).7p 4F* | 实测值 | NIST | |
| 421.80204 nm | 740 | Ac I | emission | 6d2.(3F).7s 4F → 6d2.(3P).7p 2D* | 实测值 | NIST | |
| 462.16811 nm | 710 | Ac I | emission | 6d2.(3F).7s 4F → 6d2.(3F).7p 4F* | 实测值 | NIST | |
| 426.8209 nm | 570 | Ac II | emission | 6d2 3F → 6d.7p 3P* | 实测值 | NIST |
扩展性质
共价半径（扩展）
- 共价半径（Pyykkö）
- 186 pm
- 共价半径（Pyykkö，双键）
- 153 pm
- 共价半径（Pyykkö，三键）
- 140 pm
范德华半径
- Alvarez
- 280 pm
- UFF
- 347.8 pm
- MM3
- 308 pm
原子半径与金属半径
- 原子半径（Rahm）
- 293 pm
编号标度
- Mendeleev
- 14
- Pettifor
- 48
- Glawe
- 33
电负性标度
- Ghosh
- 0
极化率与色散
- 偶极极化率
- 203 a.u.
- 偶极极化率（不确定度）
- 12 a.u.
相变与同素异形体
| 熔点 | 1323.15 K |
| 沸点 | 3473.15 K |
氧化态分类
高级参考数据
晶体半径详情 (2)
| 电荷 | CN | 自旋 | rcrystal (pm) | 来源 |
|---|---|---|---|---|
| 3 | VI | 126 | from r^3 vs V plots, | |
| 3 | IX | — | 136 |
同位素衰变方式 (56)
| 同位素 | 模式 | 强度 |
|---|---|---|
| 205 | A | 100% |
| 205 | B+ | — |
| 206 | A | 100% |
| 206 | B+ | — |
| 207 | A | 100% |
| 208 | A | 100% |
| 208 | B+ | — |
| 209 | A | 100% |
| 209 | B+ | — |
| 210 | A | 100% |
X射线散射因子 (516)
| 能量 (eV) | f₁ | f₂ |
|---|---|---|
| 10 | — | 1.19484 |
| 10.1617 | — | 1.15672 |
| 10.3261 | — | 1.11982 |
| 10.4931 | — | 1.0841 |
| 10.6628 | — | 1.04952 |
| 10.8353 | — | 1.01604 |
| 11.0106 | — | 0.98234 |
| 11.1886 | — | 0.94669 |
| 11.3696 | — | 0.91233 |
| 11.5535 | — | 0.88152 |
补充数据
Estimated Crustal Abundance
The estimated element abundance in the earth's crust.
5.5×10-10 milligrams per kilogram
参考文献 (1)
- [5] Actinium https://education.jlab.org/itselemental/ele089.html
Estimated Oceanic Abundance
The estimated element abundance in the earth's oceans.
Not Applicable
参考文献 (1)
- [5] Actinium https://education.jlab.org/itselemental/ele089.html
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.
Thomas Jefferson National Accelerator Facility (Jefferson Lab) is one of 17 national laboratories funded by the U.S. Department of Energy. The lab's primary mission is to conduct basic research of the atom's nucleus using the lab's unique particle accelerator, known as the Continuous Electron Beam Accelerator Facility (CEBAF). For more information visit https://www.jlab.org/
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 Actinium.
The element property data was retrieved from publications.