Lanthanum (La)
lanthanideSolid
标准原子量
138.90547 u电子排布
[Xe] 6s2 5d1熔点
917.85 °C沸点
3463.85 °C密度
6150 kg/m³氧化态
0, +1, +2, +3电负性（鲍林）
1.1第一电离能
5.5769 eV发现年份
1839原子半径
195 pm详细信息
Lanthanum is the first element of the lanthanide series by common convention, although its 4f shell is empty in the neutral atom. It is a soft, reactive rare-earth metal that occurs with other light rare earths in minerals such as monazite and bastnäsite. Its chemistry is dominated by the large La³⁺ ion, which gives mostly colorless, strongly ionic compounds. Lanthanum is important in optical glass, catalysts, battery alloys, and high-temperature ceramic materials.
Lanthanum is silvery white, malleable, ductile, and soft enough to be cut with a knife. It is one of the most reactive of the rare-earth metals. It oxidizes rapidly when exposed to air. Cold water attacks lanthanum slowly, while hot water attacks it much more rapidly.
The metal reacts directly with elemental carbon, nitrogen, boron, selenium, silicon, phosphorus, sulfur, and with halogens.
At 310°C, lanthanum changes from a hexagonal to a face-centered cubic structure, and at 865°C it again transforms into a body-centered cubic structure.
The name derives from the Greek lanthanein for "to be hidden" or "to escape notice" because it hid in cerium ore and was difficult to separate from that rare earth mineral. Lanthanum was discovered by the Swedish surgeon and chemist Carl-Gustav Mosander in 1839. In 1842, Mosander separated his lanthanium sample into two oxides; for one of these he retained the name lanthanum and for the other he gave the name didymium (or twin).
Lanthanum was discovered by Carl Gustaf Mosander, a Swedish chemist, in 1839. Mosander was searching for impurities he believed existed within samples of cerium. He treated cerium nitrate (Ce(NO3)3) with dilute nitric acid (HNO3) and found a new substance he named lanthana (La2O3). Roughly 0.0018% of the earth's crust is composed of lanthanum. Today, lanthanum is primarily obtained through an ion exchange process from monazite sand ((Ce, La, Th, Nd, Y)PO4), a material rich in rare earth elements that can contain as much as 25% lanthanum.
From the Greek word lanthanein, to escape notice. Mosander in 1839 extracted lanthana from impure cerium nitrate and recognized the new element.
Lanthanum was isolated in relatively pure form in 1923. Iron exchange and solvent extraction techniques have led to much easier isolation of the so-called "rare-earth" elements.
Pure lanthanum is a silvery-white, soft metal that can be cut with a knife when freshly prepared. It tarnishes rapidly in air, forming oxide and hydroxide films, and reacts slowly with cold water but more rapidly when finely divided or heated.
Lanthanum is used in high-refractive-index optical glasses for camera lenses, microscopes, and other precision optics. Mixed rare-earth metal rich in lanthanum has been used in lighter flints and spark-producing alloys. Lanthanum-containing nickel-metal hydride battery alloys store hydrogen reversibly. Lanthanum compounds are also used in fluid catalytic cracking catalysts, ceramic capacitors and dielectric materials, phosphors, and as additives in tungsten electrodes and specialty steels.
Lanthanum is one of the rare earth elements used to make carbon arc lights which are used in the motion picture industry for studio lighting and projector lights. Lanthanum also makes up about 25% of Misch metal, a material that is used to make flints for lighters. Lanthana (La2O3) is used to make the glass used in camera lenses and in other special glasses.
Rare-earth compounds containing lanthanum are extensively used in carbon lighting applications, especially by the motion picture industry for studio lighting and projection. This application consumes about 25 percent of the rare-earth compounds produced. La2O3 improves the alkali resistance of glass, and is used in making special optical glasses. Small amounts of lanthanum, as an additive, can be used to produce nodular cast iron.
There is current interest in hydrogen sponge alloys containing lanthanum. These alloys take up to 400 times their own volume of hydrogen gas, and the process is reversible. Every time they take up the gas, heat energy is released; therefore these alloys have possibilities in an energy conservation system.
Isotopes in Earth/Planetary Science
Studies have shown that 138La (with a half-life of 1.06×1011 years) can be used along with 138Ce and 136Ce to measure time elapsed from a supernova explosion producing large numbers of neutrinos [415] T. Hayakawa, T. Shizuma, T. Kajino, K. Ogawa, H. Nakada. Am. Phys. Soc.77, (2008)..
Isotopes in Geochronology
138La decays to 138Ce and 138Ba, respectively, by beta decay with a half-life of 1.06×1011 years and by electron capture with a half-life of 1.56×1011 years. The isotope-amount ratio n(138Ce)/n(142Ce) has been used for dating rocks on long time scales (billions of years) and as a chemical tracer in geochemistry [416] T. Hayashi, M. Tanimizu, T. Tanaka. Precambrian Res.135, 345 (2004).. The increase in radiogenic 138Ba in rocks enriched in rare earth elements, such as allanite, enables one to determine the age of such rocks (Fig. IUPAC.57.1) [417] S. Nakai, H. Shimizu, A. Masuda. Nature320, 433 (1986)..
Isotopes Used as a Source of Radioactive Isotope(s)
139La is used for the production of the medical radioisotope 139Ce via the 139La (p, n) 139Ce reaction [418] H. Aglan, S. A. Kandil, H. A. Hanafi, M. A. Mousa, Z. A. Saleh. J. Radioanal. Nucl. Chem.280, 533 (2009)..
Lanthanum almost exclusively forms compounds in the +3 oxidation state. Lanthanum oxide (La₂O₃) is a basic oxide used in optical glass and ceramics and readily absorbs moisture and CO₂ from air. Lanthanum chloride (LaCl₃), lanthanum nitrate (La(NO₃)₃), and lanthanum carbonate (La₂(CO₃)₃) are common salts of the La³⁺ ion. Lanthanum hexaboride (LaB₆) is a refractory conductor valued as an electron-emission material. Lanthanum strontium manganite, often written La₁₋ₓSrₓMnO₃, is important in oxide electronics and solid oxide fuel-cell cathodes.
See more information at the Lanthanum compound page.
Metallic lanthanum dust and turnings are flammable, and the metal reacts with moisture to release hydrogen. Soluble lanthanum salts can irritate skin, eyes, and the respiratory tract and may disturb calcium-related biological processes at sufficient exposure. Lanthanum has no established essential biological role. Natural lanthanum is effectively stable; radiological risk normally comes from associated thorium or uranium in ores, not from lanthanum itself.
Lanthanum and its compounds have a low to moderate acute toxicity rating; therefore, care should be taken in handling them.
Lanthanum occurs dispersed in the crust with other rare-earth elements and is concentrated mainly in phosphate and carbonate minerals. Weathering releases La³⁺ into soils and waters, where it tends to bind strongly to clays, organic matter, phosphates, and carbonates rather than remain highly mobile. Mining and processing can increase local rare-earth, acid, fluoride, and radionuclide burdens, depending on ore type and waste management.
Lanthanum is obtained chiefly as a co-product of rare-earth mining and separation, especially from bastnäsite and monazite concentrates. Separation relies on solvent extraction or ion-exchange processes because neighboring rare earths have very similar chemistry. It is one of the more abundant and lower-cost rare earths, but supply depends on integrated rare-earth processing capacity and demand for other elements in the same ores. Recycling occurs in limited streams such as nickel-metal hydride batteries and some catalysts, while optical glass and ceramics are less commonly recovered for lanthanum content.
Lanthanum is found in rare-earth minerals such as cerite, monazite, allanite, and bastnasite. Monazite and bastnasite are principal ores in which lanthanum occurs in percentages up to 25 percent and 38 percent respectively. Misch metal, used in making lighter flints, contains about 25 percent lanthanum.
The availability of lanthanum and other rare earths has improved greatly in recent years. The metal can be produced by reducing the anhydrous fluoride with calcium.
Lanthanum is an odd-atomic-number heavy element made mainly by neutron-capture processes followed by radioactive decay in earlier generations of stars. It is far less abundant cosmically than iron-group elements but is measurable in the Sun, meteorites, and many old stars. Its abundance pattern helps distinguish slow and rapid neutron-capture contributions in stellar material.
- Lanthanum metal expands when it solidifies, an uncommon behavior among metals.
- The name comes from Greek lanthanein, meaning to lie hidden, because it was found concealed in cerium minerals.
- La³⁺ is diamagnetic because it has no 4f electrons.
- Lanthanum hexaboride cathodes can emit electrons efficiently at high temperature.
- Lanthanum carbonate is used as a phosphate binder in some medical applications.
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
- 207 pm 比较所有元素的共价半径 →
- 范德华半径
- 240 pm 比较所有元素的范德华半径 →
- 金属半径
- 169 pm 比较所有元素的金属半径 →
- 密度
- 6150 kg/m³ 比较所有元素的密度 →
- 摩尔体积
- 0.0225 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
- 917.85 °C 比较所有元素的熔点 →
- 沸点
- 3463.85 °C 比较所有元素的沸点 →
- 热导率
- 13.4 W/(m·K) 比较所有元素的热导率 →
- 比热容
- 0.195 J/(g·K) 比较所有元素的比热容 →
- 摩尔热容
- 27.11 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）
- 1.1 比较所有元素的电负性（鲍林） →
- 电子亲和能
- 0.47 eV
- 第一电离能
- 5.5769 eV 比较所有元素的第一电离能 →
- 第二电离能
- 11.184999 eV 比较所有元素的第二电离能 →
- 第三电离能
- 19.177366 eV 比较所有元素的第三电离能 →
- 第四电离能
- 49.950172 eV 比较所有元素的第四电离能 →
- 第五电离能
- 61.600212 eV 比较所有元素的第五电离能 →
- 氧化态
- 0, +1, +2, +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
- [Xe] 6s2 5d1
热力学性质
- 熔化热
- 0.06425869 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
- 4.467016 eV
- 原子化热
- 4.467016 eV
- 原子化焓
- 4.467016 eV
核性质
- 质子
- 57 比较所有元素的质子 →
- 中子
- 82 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
- 1 比较所有元素的稳定同位素 →
- 最稳定同位素
- La-139
- 发现年份
- 1839
丰度
- 丰度（地壳）
- 39 mg/kg 比较所有元素的丰度（地壳） →
- 丰度（海洋）
- 3.4 × 10−6 mg/L 比较所有元素的丰度（海洋） →
晶体结构
- 晶格常数a
- 375 pm
电子结构
- 各电子层电子数
- 2, 8, 18, 18, 9, 2 比较所有元素的各电子层电子数 →
标识符
- CAS登记号
- 7439-91-0 比较所有元素的CAS登记号 →
- 谱项符号
- 2D3/2
- InChI
- InChI=1S/La
- InChI Key
- FZLIPJUXYLNCLC-UHFFFAOYSA-N
电子排布 实测值
La: 5d¹ 6s²[Xe] 5d¹ 6s²1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 5s² 5p⁶ 5d¹ 6s²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 |
|---|---|---|---|
| 139 稳定 | 138.9063563 ± 0.0000024 | 99.9112% | 稳定 |
物相 / 状态
原因: 低于熔点（917.85 °C）892.9 °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57项。 按离子电荷升序排列。
收录谱线 ?
| 离子 | 电荷 | 谱线总数 | 跃迁概率 | 能级标记 |
|---|---|---|---|---|
| La I | 0 | 393 | 315 | 393 |
| La II | +1 | 273 | 84 | 273 |
| La III | +2 | 122 | 0 | 0 |
| La IV | +3 | 87 | 0 | 0 |
| La V | +4 | 42 | 0 | 0 |
收录能级 ?
| 离子 | 电荷 | 能级 |
|---|---|---|
| La I | 0 | 343 |
| La II | +1 | 119 |
| La III | +2 | 42 |
| La IV | +3 | 52 |
| La V | +4 | 37 |
| La VI | +5 | 2 |
| La VII | +6 | 2 |
| La VIII | +7 | 2 |
| La IX | +8 | 2 |
| La X | +9 | 2 |
离子半径
| 电荷 | 配位 | 自旋 | 半径 |
|---|---|---|---|
| +3 | 6 | 暂无 | 103.2 pm |
| +3 | 7 | 暂无 | 110.00000000000001 pm |
| +3 | 8 | 暂无 | 115.99999999999999 pm |
| +3 | 9 | 暂无 | 121.6 pm |
| +3 | 10 | 暂无 | 127 pm |
| +3 | 12 | 暂无 | 136 pm |
化合物
同位素 (1)
Natural lanthanum is a mixture of two stable isotopes, 138La and 139La. Twenty three other radioactive isotopes are recognized.
| 质量数 | 原子质量（u） | 天然丰度 | 半衰期 | 衰变方式 | |
|---|---|---|---|---|---|
| 139 稳定 | 138.9063563 ± 0.0000024 | 99.9112% ± 0.0007% | 稳定 | stable |
扩展性质
共价半径（扩展）
- 共价半径（Pyykkö）
- 180 pm
- 共价半径（Pyykkö，双键）
- 139 pm
- 共价半径（Pyykkö，三键）
- 139 pm
范德华半径
- Batsanov
- 250 pm
- Alvarez
- 298 pm
- UFF
- 352.2 pm
- MM3
- 278 pm
原子半径与金属半径
- 原子半径（Rahm）
- 284 pm
- 金属半径（C12）
- 187 pm
编号标度
- Mendeleev
- 13
- Pettifor
- 33
- Glawe
- 32
电负性标度
- Ghosh
- 0
- Miedema
- 3
- Gunnarsson–Lundqvist
- 4
- Robles–Bartolotti
- 3
极化率与色散
- 偶极极化率
- 215 a.u.
- 偶极极化率（不确定度）
- 20 a.u.
- C₆ (Gould–Bučko)
- 3730 Ha·Bohr6
化学亲和力
- 质子亲和能
- 1013 kJ/mol
- 气相碱性
- 991.9 kJ/mol
Miedema参数
- Miedema摩尔体积
- 22.55 cm3/mol
- Miedema电子密度
- 2
供应风险与经济性
- 生产集中度
- 97
- 相对供应风险
- 10
- 储量分布
- 50
- 政治稳定性（最大生产国）
- 24
- 政治稳定性（最大储量国）
- 24
相变与同素异形体
| 熔点 | 1193.15 K |
| 沸点 | 3737.15 K |
氧化态分类
高级参考数据
屏蔽常数 (13)
| n | 轨道 | σ |
|---|---|---|
| 1 | s | 1.1317 |
| 2 | p | 4.2044 |
| 2 | s | 15.0466 |
| 3 | d | 13.9398 |
| 3 | p | 18.8604 |
| 3 | s | 19.0569 |
| 4 | d | 32.2748 |
| 4 | f | 55.64 |
| 4 | p | 29.2936 |
| 4 | s | 28.2036 |
晶体半径详情 (6)
| 电荷 | CN | 自旋 | rcrystal (pm) | 来源 |
|---|---|---|---|---|
| 3 | VI | 117.2 | from r^3 vs V plots, | |
| 3 | VII | 124 | ||
| 3 | VIII | 130 | from r^3 vs V plots, | |
| 3 | IX | 135.6 | from r^3 vs V plots, | |
| 3 | X | 141 | ||
| 3 | XII | 150 | calculated, |
同位素衰变方式 (64)
| 同位素 | 模式 | 强度 |
|---|---|---|
| 116 | B+ | — |
| 116 | B+p | — |
| 116 | p | — |
| 117 | p | 100% |
| 117 | B+ | — |
| 117 | B+p | — |
| 118 | B+ | — |
| 118 | B+p | — |
| 119 | B+ | — |
| 120 | B+ | 100% |
X射线散射因子 (711)
| 能量 (eV) | f₁ | f₂ |
|---|---|---|
| 10 | — | 3.31251 |
| 10.1152 | — | 3.28769 |
| 10.2317 | — | 3.26306 |
| 10.3496 | — | 3.23861 |
| 10.4688 | — | 3.20975 |
| 10.5894 | — | 3.15961 |
| 10.7114 | — | 3.11024 |
| 10.8348 | — | 3.06165 |
| 10.9596 | — | 3.01382 |
| 11.0859 | — | 2.96673 |
补充数据
Estimated Crustal Abundance
The estimated element abundance in the earth's crust.
3.9×101 milligrams per kilogram
参考文献 (1)
- [5] Lanthanum https://education.jlab.org/itselemental/ele057.html
Estimated Oceanic Abundance
The estimated element abundance in the earth's oceans.
3.4×10-6 milligrams per liter
参考文献 (1)
- [5] Lanthanum https://education.jlab.org/itselemental/ele057.html
Sources
Sources of this element.
Lanthanum is found in rare-earth minerals such as cerite, monazite, allanite, and bastnasite. Monazite and bastnasite are principal ores in which lanthanum occurs in percentages up to 25 percent and 38 percent respectively. Misch metal, used in making lighter flints, contains about 25 percent lanthanum.
The availability of lanthanum and other rare earths has improved greatly in recent years. The metal can be produced by reducing the anhydrous fluoride with calcium.
参考文献 (1)
- [6] Lanthanum https://periodic.lanl.gov/57.shtml
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 Lanthanum.
The element property data was retrieved from publications.