Gadolinium (Gd)
lanthanideSolid
Peso atomico standard
157,25 uConfigurazione elettronica
[Xe] 6s2 4f7 5d1Punto di fusione
1312,85 °CPunto di ebollizione
3272,85 °CDensità
7900 kg/m³Stati di ossidazione
0, +1, +2, +3Elettronegatività (Pauling)
1,2Energia di ionizzazione (1ª)
6,1498 eVAnno della scoperta
1886Raggio atomico
180 pmDettagli
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.
Immagini
Proprietà
Fisiche
- Raggio atomico (empirico)
- 180 pm Confronta Raggio atomico (empirico) di tutti gli elementi →
- Raggio covalente
- 196 pm Confronta Raggio covalente di tutti gli elementi →
- Raggio di van der Waals
- 237 pm Confronta Raggio di van der Waals di tutti gli elementi →
- Densità
- 7900 kg/m³ Confronta Densità di tutti gli elementi →
- Volume molare
- 0,0199 L/mol
- Fase in condizioni STP
- Solido Confronta Fase in condizioni STP di tutti gli elementi →
- Punto di fusione
- 1312,85 °C Confronta Punto di fusione di tutti gli elementi →
- Punto di ebollizione
- 3272,85 °C Confronta Punto di ebollizione di tutti gli elementi →
- Capacità termica specifica
- 0,236 J/(g·K) Confronta Capacità termica specifica di tutti gli elementi →
- Capacità termica molare
- 37,03 J/(mol·K) Confronta Capacità termica molare di tutti gli elementi →
- Struttura cristallina
- Esagonale compatta Confronta Struttura cristallina di tutti gli elementi →
Chimiche
- Elettronegatività (Pauling)
- 1,2 Confronta Elettronegatività (Pauling) di tutti gli elementi →
- Affinità elettronica
- 0,132 eV
- Energia di ionizzazione (1ª)
- 6,1498 eV Confronta Energia di ionizzazione (1ª) di tutti gli elementi →
- Energia di ionizzazione (2ª)
- 12,076042 eV Confronta Energia di ionizzazione (2ª) di tutti gli elementi →
- Energia di ionizzazione (3ª)
- 20,540071 eV Confronta Energia di ionizzazione (3ª) di tutti gli elementi →
- Energia di ionizzazione (4ª)
- 44,440153 eV Confronta Energia di ionizzazione (4ª) di tutti gli elementi →
- Energia di ionizzazione (5ª)
- 64,800223 eV Confronta Energia di ionizzazione (5ª) di tutti gli elementi →
- Stati di ossidazione
- 0, +1, +2, +3 Confronta Stati di ossidazione di tutti gli elementi →
- Elettroni di valenza
- 3 Confronta Elettroni di valenza di tutti gli elementi →
- Configurazione elettronica
- [Xe] 6s2 4f7 5d1
Termodinamiche
- Calore di fusione
- 0,10364305 eV Confronta Calore di fusione di tutti gli elementi →
- Calore di vaporizzazione
- 3,109292 eV Confronta Calore di vaporizzazione di tutti gli elementi →
- Calore di sublimazione
- 4,124994 eV
- Calore di atomizzazione
- 4,124994 eV
- Entalpia di atomizzazione
- 4,119811 eV
Nucleari
- Protoni
- 64 Confronta Protoni di tutti gli elementi →
- Neutroni
- 94 Confronta Neutroni di tutti gli elementi →
- Isotopi noti
- 40 Confronta Isotopi noti di tutti gli elementi →
- Isotopi stabili
- 5 Confronta Isotopi stabili di tutti gli elementi →
- Isotopo più stabile
- Gd-158
- Anno della scoperta
- 1886
Abbondanza
- Abbondanza (crosta terrestre)
- 6,2 mg/kg Confronta Abbondanza (crosta terrestre) di tutti gli elementi →
- Abbondanza (oceano)
- 7 × 10−7 mg/L Confronta Abbondanza (oceano) di tutti gli elementi →
Struttura cristallina
- Costante reticolare a
- 364 pm
Struttura elettronica
- Elettroni per guscio
- 2, 8, 18, 25, 9, 2 Confronta Elettroni per guscio di tutti gli elementi →
Identificativi
- Numero CAS
- 7440-54-2 Confronta Numero CAS di tutti gli elementi →
- Simbolo di termine
- 9D°2
- InChI
- InChI=1S/Gd
- Chiave InChI
- UIWYJDYFSGRHKR-UHFFFAOYSA-N
Configurazione elettronica Misurato
Gd: 4f⁷ 5d¹ 6s²[Xe] 4f⁷ 5d¹ 6s²1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 5s² 5p⁶ 4f⁷ 5d¹ 6s²Modello atomico
Gli isotopi modificano il numero di neutroni, la massa e la stabilità — non la configurazione elettronica di un atomo neutro.
Modello atomico schematico, non in scala.
Impronta atomica
Spettro di emissione / assorbimento
Distribuzione isotopica
| Numero di massa | Massa atomica (u) | Abbondanza naturale | Emivita |
|---|---|---|---|
| 154 Stabile | 153,9208741 ± 0,0000017 | 2,1800% | Stabile |
| 155 Stabile | 154,9226305 ± 0,0000017 | 14,8000% | Stabile |
| 156 Stabile | 155,9221312 ± 0,0000017 | 20,4700% | Stabile |
| 157 Stabile | 156,9239686 ± 0,0000017 | 15,6500% | Stabile |
| 158 Stabile | 157,9241123 ± 0,0000017 | 24,8400% | Stabile |
Fase / Stato
Motivo: 1287,8 °C sotto il punto di fusione (1312,85 °C)
Schema non in scala
Punti di transizione di fase
Energie di transizione
Energia necessaria per fondere 1 mol al punto di fusione
Energia necessaria per vaporizzare 1 mol al punto di ebollizione
Energia necessaria per sublimare 1 mol al punto di sublimazione
Densità
In condizioni standard
In condizioni standard
Spettri atomici
Sono visualizzati 10 di 64. Ordinamento per carica ionica crescente.
Righe disponibili ?
| Ione | Carica | Righe totali | Probabilità di transizione | Designazioni dei livelli |
|---|---|---|---|---|
| Gd I | 0 | 371 | 16 | 19 |
| Gd II | +1 | 465 | 0 | 17 |
| Gd III | +2 | 158 | 0 | 0 |
| Gd IV | +3 | 50 | 0 | 0 |
Livelli disponibili ?
| Ione | Carica | Livelli |
|---|---|---|
| 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 |
Raggi ionici
| Carica | Coordinazione | Spin | Raggio |
|---|---|---|---|
| +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 |
Composti
Isotopi (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.
| Numero di massa | Massa atomica (u) | Abbondanza naturale | Emivita | Modalità di decadimento | |
|---|---|---|---|---|---|
| 154 Stabile | 153,9208741 ± 0,0000017 | 2,1800% ± 0,0300% | Stabile | stable | |
| 155 Stabile | 154,9226305 ± 0,0000017 | 14,8000% ± 0,1200% | Stabile | stable | |
| 156 Stabile | 155,9221312 ± 0,0000017 | 20,4700% ± 0,0900% | Stabile | stable | |
| 157 Stabile | 156,9239686 ± 0,0000017 | 15,6500% ± 0,0200% | Stabile | stable | |
| 158 Stabile | 157,9241123 ± 0,0000017 | 24,8400% ± 0,0700% | Stabile | stable |
Proprietà estese
Raggi covalenti (dati estesi)
- Raggio covalente (Pyykkö)
- 169 pm
- Raggio covalente (Pyykkö, legame doppio)
- 135 pm
- Raggio covalente (Pyykkö, legame triplo)
- 132 pm
Raggi di van der Waals
- Alvarez
- 283 pm
- UFF
- 336,8 pm
- MM3
- 271 pm
Raggi atomici e metallici
- Raggio atomico (Rahm)
- 277 pm
Scale di numerazione
- Mendeleev
- 27
- Pettifor
- 27
- Glawe
- 26
Scale di elettronegatività
- Ghosh
- 0
- Miedema
- 3
- Gunnarsson–Lundqvist
- 7
- Robles–Bartolotti
- 6
Polarizzabilità e dispersione
- Polarizzabilità dipolare
- 158 a.u.
- Polarizzabilità dipolare (inc.)
- 20 a.u.
- C₆ (Gould–Bučko)
- 2340 Ha·Bohr6
Parametri di Miedema
- Volume molare di Miedema
- 19,9 cm3/mol
- Densità elettronica di Miedema
- 2
Rischio di approvvigionamento ed economia
- Concentrazione della produzione
- 97
- Rischio relativo di approvvigionamento
- 10
- Distribuzione delle riserve
- 50
- Stabilità politica (principale produttore)
- 24
- Stabilità politica (principale detentore di riserve)
- 24
Transizioni di fase e allotropi
| Punto di fusione | 1586,15 K |
| Punto di ebollizione | 3546,15 K |
Categorie degli stati di ossidazione
Dati di riferimento avanzati
Costanti di schermaggio (13)
| n | Orbitale | 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 |
Dettaglio dei raggi cristallini (4)
| Carica | CN | Spin | rcrystal (pm) | Origine |
|---|---|---|---|---|
| 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, |
Modalità di decadimento degli isotopi (57)
| Isotopo | Modalità | Intensità |
|---|---|---|
| 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 | — |
Fattori di diffusione dei raggi 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 |
Dati aggiuntivi
Estimated Crustal Abundance
The estimated element abundance in the earth's crust.
6.2 milligrams per kilogram
Riferimenti (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
Riferimenti (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.
Riferimenti (1)
- [6] Gadolinium https://periodic.lanl.gov/64.shtml
Riferimenti
(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.