Gadolinium (Gd)
lanthanideSolid
Peso atômico padrão
157,25 uConfiguração eletrônica
[Xe] 6s2 4f7 5d1Ponto de fusão
1312,85 °CPonto de ebulição
3272,85 °CDensidade
7900 kg/m³Estados de oxidação
0, +1, +2, +3Eletronegatividade (Pauling)
1,2Energia de ionização (1ª)
6,1498 eVAno da descoberta
1886Raio atômico
180 pmDetalhes
Gadolinium is a silvery lanthanide metal and one of the middle rare-earth elements. Its chemistry is dominated by the +3 oxidation state, but its seven unpaired 4f electrons give it unusually strong magnetic behavior for a rare-earth element. Natural gadolinium is a mixture of stable isotopes, with ¹⁵²Gd very long-lived and weakly radioactive. The element is technologically important in magnetic materials, neutron absorption, phosphors, and medical contrast agents.
As with other related rare-earth metals, gadolinium is silvery white, has a metallic luster, and is malleable and ductile. At room temperature, gadolinium crystallizes in the hexagonal, close-packed alpha form. Upon heating to 1235°C, alpha gadolinium transforms into the beta form, which has a body-centered cubic structure.
The metal is relatively stable in dry air, but tarnishes in moist air and forms a loosely adhering oxide film which falls off and exposes more surface to oxidation. The metal reacts slowly with water and is soluble in dilute acid.
Gadolinium has the highest thermal neutron capture cross-section of any known element (49,000 barns).
The name derives from the mineral gadolinite, in which it was found, and that had been named for the Finnish rare earth chemist Johan Gadolin. Gadolinium was discovered by the Swiss chemist Jean-Charles Galissard de Marignac in 1886, who produced a white oxide in a samarskite mineral. In 1886, the French chemist Paul-Emile Lecoq de Boisbaudran gave the name gadolinium.
Spectroscopic evidence for the existence of gadolinium was first observed by the Swiss chemist Jean Charles Galissard de Marignac in the minerals didymia and gadolinite ((Ce, La, Nd, Y)2FeBe2Si2O10) in 1880. Today, gadolinium is primarily obtained from the minerals monazite ((Ce, La, Th, Nd, Y)PO4) and bastnasite ((Ce,La,Y)CO3F).
From gadolinite, a mineral named for Gadolin, a Finnish chemist. The rare earth metal is obtained from the mineral gadolinite. Gadolinia, the oxide of gadolinium, was separated by Marignac in 1880 and Lecoq de Boisbaudran independently isolated it from Mosander's yttria in 1886.
Pure gadolinium is a soft, bright, silvery-white metal when freshly cut. It tarnishes in air and can form a darker oxide surface. At ordinary pressure it is ferromagnetic below about 20 °C, close enough to room temperature that modest temperature changes strongly affect its magnetism.
Gadolinium is used where high magnetic moment or high neutron-capture ability is valuable. Gadolinium compounds are used in some magnetic resonance imaging contrast agents, where chelation is essential to control toxicity. Gadolinium oxide is used in phosphors and scintillators, and gadolinium gallium garnet has served as a substrate and optical material. Gadolinium is also used in control materials and burnable neutron absorbers in some nuclear reactors, often as gadolinium oxide mixed into fuel.
Gadolinium has the greatest ability to capture thermal neutrons of all known elements and can be used as control rods for nuclear reactors. Unfortunately, the two isotopes best suited for neutron capture, gadolinium-155 and gadolinium-157, are present in gadolinium in small amounts. As a result, gadolinium control rods quickly lose their effectiveness.
Gadolinium can be combined with yttrium to form garnets that have applications in microwave technology. Gadolinium can be alloyed with iron, chromium and other metals to improve their workability and their resistance to high temperatures and oxidation. Gadolinium compounds are used to make phosphors for color televisions.
Gadolinium yttrium garnets are used in microwave applications and gadolinium compounds are used as phosphors in color television sets.
The metal has unusual superconductive properties. As little as 1 percent gadolinium improves the workability and resistance of iron, chromium, and related alloys to high temperatures and oxidation.
Gadolinium ethyl sulfate has extremely low noise characteristics and may find use in duplicating the performance of amplifiers, such as the maser.
The metal is ferromagnetic. Gadolinium is unique for its high magnetic movement and for its special Curie temperature (above which ferromagnetism vanishes) lying just at room temperature, meaning it could be used as a magnetic component that can sense hot and cold.
Isotopes in Earth/Planetary Science
The lunar surface is continuously exposed to cosmic radiation, and the interaction between planetary material and cosmic rays produces secondary neutrons. The neutron flux can be investigated using the large neutron capture cross sections of 149Sm, 155Gd, and 157Gd. For example, 157Gd will absorb neutrons and be converted to 158Gd. On a cross plot of n(158Gd)/n(160Gd) isotope-amount ratio and n(157Gd)/n(160Gd) isotope-amount ratio (Fig. IUPAC.64.1), values will move from the lower right corner to the upper left corner of the cross plot with increasing time or increasing flux.
Isotopes in Medicine
The addition of 157Gd to Neutron Capture Therapy (NCT) has been shown to be more effective at targeting tumors than the previous method of using only 10B for the treatment (Fig. IUPAC.64.2) [453] C. N. Culbertson, T. Jevremovic. Phys. Med. Biol.48, 3943 (2003).. 153Gd (with a half-life of 0.66 years) is used in the production of photon line sources (an optical source that emits one or more spectrally narrow lines as opposed to a continuous spectrum) to manufacture 153Gd line sources [454] V. M. Lebedev, J. N. Gordeev, E. A. Karelin, V. D. Gavrilov. Appl. Radiat. Isot.53, 829 (2000).. 153Gd is also used as a photon source of the dual-photon absorptiometry (DPA) technique that is used to measure bone mineral content (BMC). Studies for this technique have been conducted in horses and humans [455] A. Moure, P. Reichmann, H. R. Gamba. Phys. Med. Biol.48, 3851 (2003)., [456] P. Tothill, M. A. Smith, D. Sutton. Br. J. Radiol.56, 829 (1983)..
Gadolinium chemistry is mainly that of Gd³⁺ salts and oxides. Gadolinium(III) oxide, Gd₂O₃, is a stable refractory oxide and a common starting material. Gadolinium(III) chloride, GdCl₃, and gadolinium(III) nitrate, Gd(NO₃)₃, form hydrated salts and coordination complexes. Gadolinium(III) sulfate, Gd₂(SO₄)₃, and many organic chelates are also important. The +2 state is known in specialized solid-state and organometallic chemistry, but it is not the normal aqueous form.
See more information at the Gadolinium compound page.
Metallic gadolinium dust can burn and should be treated as a reactive metal powder. Soluble gadolinium salts are toxic at sufficient dose, largely because free Gd³⁺ can interfere with calcium-dependent biological processes. Medical contrast agents use tightly bound complexes, but release or retention of gadolinium is a recognized safety concern, especially in vulnerable patients. Stable gadolinium isotopes do not present a radiological hazard of practical importance.
Gadolinium occurs in nature dispersed with other rare-earth elements in minerals such as monazite and bastnäsite. It is not known to have an essential biological role. In soils and waters it tends to bind strongly to minerals, phosphates, carbonates, and organic matter rather than remain as a simple free ion. Anthropogenic gadolinium from contrast agents can pass through wastewater systems and has been detected as anomalous rare-earth patterns in some surface waters.
Gadolinium is not mined as a primary metal. It is recovered during processing of rare-earth ores, with separation from chemically similar lanthanides by solvent extraction or ion-exchange methods. Supply depends on the rare-earth industry as a whole and on the economics of separating mixed concentrates into individual oxides. Demand is smaller than for neodymium or cerium but important in medical imaging, nuclear technology, phosphors, and specialty magnetic materials. Recycling is limited and is most practical from concentrated industrial scrap rather than diffuse medical releases.
Gadolinium is found in several other minerals, including monazite and bastnasite, both of which are commercially important. With the development of ion-exchange and solvent extraction techniques, the availability and prices of gadolinium and the other rare-earth metals have greatly improved. The metal can be prepared by the reduction of the anhydrous fluoride with metallic calcium.
Gadolinium is a heavy element made mainly by neutron-capture processes in earlier generations of stars. Its stable isotopes include products associated with both slow and rapid neutron capture. In the Solar System it is far less abundant than iron or the light elements, but it follows the general rare-earth pattern in meteorites and planetary materials.
- Natural gadolinium has one of the highest thermal-neutron absorption capacities among stable-element mixtures.
- The element is named through gadolinite, a mineral ultimately named for Johan Gadolin.
- Gadolinium becomes ferromagnetic only just below ordinary room temperature.
- Free Gd³⁺ is far more hazardous than gadolinium held in approved chelating ligands.
- Gadolinium anomalies in rivers can trace releases from medical imaging agents.
Imagens
Propriedades
Física
- Raio atômico (empírico)
- 180 pm Comparar Raio atômico (empírico) de todos os elementos →
- Raio covalente
- 196 pm Comparar Raio covalente de todos os elementos →
- Raio de van der Waals
- 237 pm Comparar Raio de van der Waals de todos os elementos →
- Densidade
- 7900 kg/m³ Comparar Densidade de todos os elementos →
- Volume molar
- 0,0199 L/mol
- Fase nas CNTP
- Sólido Comparar Fase nas CNTP de todos os elementos →
- Ponto de fusão
- 1312,85 °C Comparar Ponto de fusão de todos os elementos →
- Ponto de ebulição
- 3272,85 °C Comparar Ponto de ebulição de todos os elementos →
- Capacidade calorífica específica
- 0,236 J/(g·K) Comparar Capacidade calorífica específica de todos os elementos →
- Capacidade calorífica molar
- 37,03 J/(mol·K) Comparar Capacidade calorífica molar de todos os elementos →
- Estrutura cristalina
- Hexagonal compacta Comparar Estrutura cristalina de todos os elementos →
Química
- Eletronegatividade (Pauling)
- 1,2 Comparar Eletronegatividade (Pauling) de todos os elementos →
- Afinidade eletrônica
- 0,132 eV
- Energia de ionização (1ª)
- 6,1498 eV Comparar Energia de ionização (1ª) de todos os elementos →
- Energia de ionização (2ª)
- 12,076042 eV Comparar Energia de ionização (2ª) de todos os elementos →
- Energia de ionização (3ª)
- 20,540071 eV Comparar Energia de ionização (3ª) de todos os elementos →
- Energia de ionização (4ª)
- 44,440153 eV Comparar Energia de ionização (4ª) de todos os elementos →
- Energia de ionização (5ª)
- 64,800223 eV Comparar Energia de ionização (5ª) de todos os elementos →
- Estados de oxidação
- 0, +1, +2, +3 Comparar Estados de oxidação de todos os elementos →
- Elétrons de valência
- 3 Comparar Elétrons de valência de todos os elementos →
- Configuração eletrônica
- [Xe] 6s2 4f7 5d1
Termodinâmica
- Calor de fusão
- 0,10364305 eV Comparar Calor de fusão de todos os elementos →
- Calor de vaporização
- 3,109292 eV Comparar Calor de vaporização de todos os elementos →
- Calor de sublimação
- 4,124994 eV
- Calor de atomização
- 4,124994 eV
- Entalpia de atomização
- 4,119811 eV
Nuclear
- Prótons
- 64 Comparar Prótons de todos os elementos →
- Nêutrons
- 94 Comparar Nêutrons de todos os elementos →
- Isótopos conhecidos
- 40 Comparar Isótopos conhecidos de todos os elementos →
- Isótopos estáveis
- 5 Comparar Isótopos estáveis de todos os elementos →
- Isótopo mais estável
- Gd-158
- Ano da descoberta
- 1886
Abundância
- Abundância (crosta terrestre)
- 6,2 mg/kg Comparar Abundância (crosta terrestre) de todos os elementos →
- Abundância (oceano)
- 7 × 10−7 mg/L Comparar Abundância (oceano) de todos os elementos →
Estrutura cristalina
- Constante de rede a
- 364 pm
Estrutura eletrônica
- Elétrons por camada
- 2, 8, 18, 25, 9, 2 Comparar Elétrons por camada de todos os elementos →
Identificadores
- Número CAS
- 7440-54-2 Comparar Número CAS de todos os elementos →
- Símbolo de termo
- 9D°2
- InChI
- InChI=1S/Gd
- Chave InChI
- UIWYJDYFSGRHKR-UHFFFAOYSA-N
Configuração eletrônica Medido
Gd: 4f⁷ 5d¹ 6s²[Xe] 4f⁷ 5d¹ 6s²1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 5s² 5p⁶ 4f⁷ 5d¹ 6s²Modelo atômico
Os isótopos alteram o número de nêutrons, a massa e a estabilidade — não a configuração eletrônica de um átomo neutro.
Modelo atômico esquemático, sem escala.
Assinatura atômica
Espectro de emissão / absorção
Distribuição isotópica
| Número de massa | Massa atômica (u) | Abundância natural | Meia-vida |
|---|---|---|---|
| 154 Estável | 153,9208741 ± 0,0000017 | 2,1800% | Estável |
| 155 Estável | 154,9226305 ± 0,0000017 | 14,8000% | Estável |
| 156 Estável | 155,9221312 ± 0,0000017 | 20,4700% | Estável |
| 157 Estável | 156,9239686 ± 0,0000017 | 15,6500% | Estável |
| 158 Estável | 157,9241123 ± 0,0000017 | 24,8400% | Estável |
Fase / Estado
Motivo: 1287,8 °C abaixo do ponto de fusão (1312,85 °C)
Esquemático, sem escala
Pontos de transição de fase
Energias de transição
Energia necessária para fundir 1 mol no ponto de fusão
Energia necessária para vaporizar 1 mol no ponto de ebulição
Energia necessária para sublimar 1 mol no ponto de sublimação
Densidade
Em condições padrão
Em condições padrão
Espectros atômicos
Mostrando 10 de 64. Ordenado por carga do íon (ordem crescente).
Dados de linhas disponíveis ?
| Íon | Carga | Total de linhas | Probabilidades de transição | Designações dos níveis |
|---|---|---|---|---|
| Gd I | 0 | 371 | 16 | 19 |
| Gd II | +1 | 465 | 0 | 17 |
| Gd III | +2 | 158 | 0 | 0 |
| Gd IV | +3 | 50 | 0 | 0 |
Dados de níveis disponíveis ?
| Íon | Carga | Níveis |
|---|---|---|
| Gd I | 0 | 634 |
| Gd II | +1 | 321 |
| Gd III | +2 | 28 |
| Gd IV | +3 | 5 |
| Gd V | +4 | 2 |
| Gd VI | +5 | 2 |
| Gd VII | +6 | 2 |
| Gd VIII | +7 | 2 |
| Gd IX | +8 | 2 |
| Gd X | +9 | 2 |
Raios iônicos
| Carga | Coordenação | Spin | Raio |
|---|---|---|---|
| +3 | 6 | N/D | 93.8 pm |
| +3 | 7 | N/D | 100 pm |
| +3 | 8 | N/D | 105.3 pm |
| +3 | 9 | N/D | 110.7 pm |
Compostos
Isótopos (5)
Natural gadolinium is a mixture of seven isotopes, but 17 isotopes of gadolinium are now recognized. Although two of these, 155Gd and 157Gd, have excellent capture characteristics, they are only present naturally in low concentrations. As a result, gadolinium has a very fast burnout rate and has limited use as a nuclear control rod material.
| Número de massa | Massa atômica (u) | Abundância natural | Meia-vida | Modo de decaimento | |
|---|---|---|---|---|---|
| 154 Estável | 153,9208741 ± 0,0000017 | 2,1800% ± 0,0300% | Estável | stable | |
| 155 Estável | 154,9226305 ± 0,0000017 | 14,8000% ± 0,1200% | Estável | stable | |
| 156 Estável | 155,9221312 ± 0,0000017 | 20,4700% ± 0,0900% | Estável | stable | |
| 157 Estável | 156,9239686 ± 0,0000017 | 15,6500% ± 0,0200% | Estável | stable | |
| 158 Estável | 157,9241123 ± 0,0000017 | 24,8400% ± 0,0700% | Estável | stable |
Propriedades ampliadas
Raios covalentes (dados ampliados)
- Raio covalente (Pyykkö)
- 169 pm
- Raio covalente (Pyykkö, ligação dupla)
- 135 pm
- Raio covalente (Pyykkö, ligação tripla)
- 132 pm
Raios de van der Waals
- Alvarez
- 283 pm
- UFF
- 336,8 pm
- MM3
- 271 pm
Raios atômicos e metálicos
- Raio atômico (Rahm)
- 277 pm
Escalas de numeração
- Mendeleev
- 27
- Pettifor
- 27
- Glawe
- 26
Escalas de eletronegatividade
- Ghosh
- 0
- Miedema
- 3
- Gunnarsson–Lundqvist
- 7
- Robles–Bartolotti
- 6
Polarizabilidade e dispersão
- Polarizabilidade dipolar
- 158 a.u.
- Polarizabilidade dipolar (incerteza)
- 20 a.u.
- C₆ (Gould–Bučko)
- 2340 Ha·Bohr6
Parâmetros de Miedema
- Volume molar de Miedema
- 19,9 cm3/mol
- Densidade eletrônica de Miedema
- 2
Risco de abastecimento e economia
- Concentração da produção
- 97
- Risco relativo de abastecimento
- 10
- Distribuição das reservas
- 50
- Estabilidade política (maior produtor)
- 24
- Estabilidade política (detentor das maiores reservas)
- 24
Transições de fase e alótropos
| Ponto de fusão | 1586,15 K |
| Ponto de ebulição | 3546,15 K |
Categorias de estados de oxidação
Dados de referência avançados
Constantes de blindagem (13)
| n | Orbital | σ |
|---|---|---|
| 1 | s | 1,2565 |
| 2 | p | 4,2946 |
| 2 | s | 16,783 |
| 3 | d | 13,723 |
| 3 | p | 19,8508 |
| 3 | s | 20,2903 |
| 4 | d | 34,3664 |
| 4 | f | 38,9864 |
| 4 | p | 31,3532 |
| 4 | s | 30,556 |
Detalhes dos raios cristalinos (4)
| Carga | CN | Spin | rcrystal (pm) | Origem |
|---|---|---|---|---|
| 3 | VI | 107,8 | from r^3 vs V plots, | |
| 3 | VII | 114 | ||
| 3 | VIII | 119,3 | from r^3 vs V plots, | |
| 3 | IX | 124,7 | from r^3 vs V plots, calculated, |
Modos de decaimento dos isótopos (57)
| Isótopo | Modo | Intensidade |
|---|---|---|
| 133 | B+ | — |
| 133 | B+p | — |
| 134 | B+ | — |
| 134 | B+p | — |
| 135 | B+ | 100% |
| 135 | B+p | 2% |
| 136 | B+ | — |
| 136 | B+p | — |
| 137 | B+ | 100% |
| 137 | B+p | — |
Fatores de espalhamento de raios X (719)
| Energia (eV) | f₁ | f₂ |
|---|---|---|
| 10 | — | 2,59886 |
| 10,1152 | — | 2,63957 |
| 10,2317 | — | 2,68119 |
| 10,3496 | — | 2,72415 |
| 10,4688 | — | 2,7678 |
| 10,5894 | — | 2,81214 |
| 10,7114 | — | 2,8572 |
| 10,8348 | — | 2,90298 |
| 10,9596 | — | 2,94949 |
| 11,0859 | — | 2,99675 |
Dados adicionais
Estimated Crustal Abundance
The estimated element abundance in the earth's crust.
6.2 milligrams per kilogram
Referências (1)
- [5] Gadolinium https://education.jlab.org/itselemental/ele064.html
Estimated Oceanic Abundance
The estimated element abundance in the earth's oceans.
7×10-7 milligrams per liter
Referências (1)
- [5] Gadolinium https://education.jlab.org/itselemental/ele064.html
Sources
Sources of this element.
Gadolinium is found in several other minerals, including monazite and bastnasite, both of which are commercially important. With the development of ion-exchange and solvent extraction techniques, the availability and prices of gadolinium and the other rare-earth metals have greatly improved. The metal can be prepared by the reduction of the anhydrous fluoride with metallic calcium.
Referências (1)
- [6] Gadolinium https://periodic.lanl.gov/64.shtml
Referências
(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 Gadolinium.
The element property data was retrieved from publications.