Lanthanum (La)
lanthanideSolid
標準原子量
138.90547 u電子配置
[Xe] 6s2 5d1融点
917.85 °C沸点
3463.85 °C密度
6150 kg/m³酸化数
0, +1, +2, +3電気陰性度（Pauling）
1.1第1イオン化エネルギー
5.5769 eV発見年
1839原子半径
195 pm詳細
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.
画像
性質
物理的性質
- 原子半径（経験値）
- 195 pm 全元素の原子半径（経験値）を比較 →
- 共有結合半径
- 207 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
- 240 pm 全元素のファンデルワールス半径を比較 →
- 金属半径
- 169 pm 全元素の金属半径を比較 →
- 密度
- 6150 kg/m³ 全元素の密度を比較 →
- モル体積
- 0.0225 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
- 917.85 °C 全元素の融点を比較 →
- 沸点
- 3463.85 °C 全元素の沸点を比較 →
- 熱伝導率
- 13.4 W/(m·K) 全元素の熱伝導率を比較 →
- 比熱容量
- 0.195 J/(g·K) 全元素の比熱容量を比較 →
- モル熱容量
- 27.11 J/(mol·K) 全元素のモル熱容量を比較 →
- 結晶構造
- 六方最密充填構造 全元素の結晶構造を比較 →
化学的性質
- 電気陰性度（Pauling）
- 1.1 全元素の電気陰性度（Pauling）を比較 →
- 電子親和力
- 0.47 eV
- 第1イオン化エネルギー
- 5.5769 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
- 11.184999 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
- 19.177366 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
- 49.950172 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
- 61.600212 eV 全元素の第5イオン化エネルギーを比較 →
- 酸化数
- 0, +1, +2, +3 全元素の酸化数を比較 →
- 価電子
- 3 全元素の価電子を比較 →
- 電子配置
- [Xe] 6s2 5d1
熱力学的性質
- 融解熱
- 0.06425869 eV 全元素の融解熱を比較 →
- 蒸発熱
- 4.145722 eV 全元素の蒸発熱を比較 →
- 昇華熱
- 4.467016 eV
- 原子化熱
- 4.467016 eV
- 原子化エンタルピー
- 4.467016 eV
原子核
- 陽子数
- 57 全元素の陽子数を比較 →
- 中性子数
- 82 全元素の中性子数を比較 →
- 既知の同位体
- 42 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
- La-139
- 発見年
- 1839
存在度
- 存在度（地殻）
- 39 mg/kg 全元素の存在度（地殻）を比較 →
- 存在度（海洋）
- 3.4 × 10−6 mg/L 全元素の存在度（海洋）を比較 →
結晶構造
- 格子定数a
- 375 pm
電子構造
- 各電子殻の電子数
- 2, 8, 18, 18, 9, 2 全元素の各電子殻の電子数を比較 →
識別子
- CAS登録番号
- 7439-91-0 全元素のCAS登録番号を比較 →
- 項記号
- 2D3/2
- InChI
- InChI=1S/La
- InChI Key
- FZLIPJUXYLNCLC-UHFFFAOYSA-N
電子配置 測定値
La: 5d¹ 6s²[Xe] 5d¹ 6s²1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 5s² 5p⁶ 5d¹ 6s²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 |
|---|---|---|---|
| 139 安定 | 138.9063563 ± 0.0000024 | 99.9112% | 安定 |
相／状態
理由: 融点（917.85 °C）より892.9 °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
融点で1 molを融解させるのに必要なエネルギー
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
原子スペクトル
全57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 |
|---|---|---|---|---|
| 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 |
準位データの収録状況 ?
| イオン | 電荷 | 準位 |
|---|---|---|
| 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 |
イオン半径
| 電荷 | 配位 | スピン | 半径 |
|---|---|---|---|
| +3 | 6 | データなし | 103.2 pm |
| +3 | 7 | データなし | 110.00000000000001 pm |
| +3 | 8 | データなし | 115.99999999999999 pm |
| +3 | 9 | データなし | 121.6 pm |
| +3 | 10 | データなし | 127 pm |
| +3 | 12 | データなし | 136 pm |
化合物
同位体 (1)
Natural lanthanum is a mixture of two stable isotopes, 138La and 139La. Twenty three other radioactive isotopes are recognized.
| 質量数 | 原子質量（u） | 天然存在比 | 半減期 | 崩壊形式 | |
|---|---|---|---|---|---|
| 139 安定 | 138.9063563 ± 0.0000024 | 99.9112% ± 0.0007% | 安定 | stable |
詳細な性質
共有結合半径（詳細）
- 共有結合半径（Pyykkö）
- 180 pm
- 共有結合半径（Pyykkö、二重結合）
- 139 pm
- 共有結合半径（Pyykkö、三重結合）
- 139 pm
ファンデルワールス半径
- Batsanov
- 250 pm
- Alvarez
- 298 pm
- UFF
- 352.2 pm
- MM3
- 278 pm
原子半径と金属半径
- 原子半径（Rahm）
- 284 pm
- 金属半径（C12）
- 187 pm
番号付けの尺度
- Mendeleev
- 13
- Pettifor
- 33
- Glawe
- 32
電気陰性度の尺度
- Ghosh
- 0
- Miedema
- 3
- Gunnarsson–Lundqvist
- 4
- Robles–Bartolotti
- 3
分極率と分散
- 双極子分極率
- 215 a.u.
- 双極子分極率（不確かさ）
- 20 a.u.
- C₆ (Gould–Bučko)
- 3730 Ha·Bohr6
化学親和力
- プロトン親和力
- 1013 kJ/mol
- 気相塩基性
- 991.9 kJ/mol
ミーデマパラメータ
- ミーデマモル体積
- 22.55 cm3/mol
- ミーデマ電子密度
- 2
供給リスクと経済性
- 生産集中度
- 97
- 相対供給リスク
- 10
- 埋蔵量の分布
- 50
- 政治的安定性（最大生産国）
- 24
- 政治的安定性（最大埋蔵国）
- 24
相転移と同素体
| 融点 | 1193.15 K |
| 沸点 | 3737.15 K |
酸化数の分類
専門参考データ
遮蔽定数 (13)
| n | 軌道 | 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 |
結晶半径の詳細 (6)
| 電荷 | CN | スピン | rcrystal (pm) | 由来 |
|---|---|---|---|---|
| 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, |
同位体の崩壊形式 (64)
| 同位体 | モード | 強度 |
|---|---|---|
| 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線散乱因子 (711)
| エネルギー (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 |
追加データ
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.