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General
States Energies Oxidation & Electrons Appearance & Characteristics Reactions Compounds Radius Conductivity Abundance & Isotopes |
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General:
| Name: Gadolinium | Symbol: Gd |
| Type: Rare Earth, Lanthanide series | Atomic weight: 157.25 |
| Density @ 293 K: 7.895 g/cm3 | Atomic volume: 19.9 cm3/mol |
| Discovered: In 1880 chemist Jean Charles Galissard de Marignac recorded previously unknown spectroscopic lines in mineral samples. These resulted from the presence of the element we now know as gadolinium. In 1886 chemist Paul Émile Lecoq de Boisbaudran isolated gadolinium oxide (gadolinia). Metallic gadolinium was not isolated until 1935. The element is named after the 18th century chemist and mineralogist Johan Gadolin. | |
States
| State (s, l, g): solid | |
| Melting point: 1587 K (1314 oC) | Boiling point: 3533 K (3260 oC) |
Energies
| Specific heat capacity: 0.23 J g-1 K-1 | Heat of atomization: 389 kJ mol-1 |
| Heat of fusion: 10.050 kJ mol-1 | Heat of vaporization : 311.71 kJ mol-1 |
| 1st ionization energy: 593.40 kJ mol-1 | 2nd ionization energy: 1170 kJ mol-1 |
| 3rd ionization energy: 1991 kJ mol-1 | Electron affinity: kJ mol-1 |
Oxidation & Electrons
| Shells: 2,8,18,25,9,2 | Electron configuration: [Xe] 4f7 5d1 6s2 |
| Minimum oxidation number: 0 | Maximum oxidation number: 3 |
| Min. common oxidation no.: 0 | Max. common oxidation no.: 3 |
| Electronegativity (Pauling Scale): 1.20 | Polarizability volume: 23.5 Å3 |
Appearance & Characteristics
| Structure: hexagonal close packed | Color: silvery-white |
| Harmful effects: Gadolinium is considered to be highly toxic. | Hardness: mohs |
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Characteristics:
Gadolinium is a bright, soft, silvery-white metal that is both ductile and malleable. It is one of the rare earth metals. It does not react in dry air but will tarnish to a flaky oxide in moist air that does not protect it from further oxidation. The metal reacts slowly with water and is soluble in dilute acid. At room temperature the metal is paramagnetic, but it becomes ferromagnetic (strongly attracted by a magnet) when cooled. The 157Gd isotope has the highest thermal neutron capture cross-section of any known stable element. |
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Uses:
Gadolinium is used in alloys of iron and chromium to improve resistance to high temperatures and oxidation. Gadolinium is used to make gadolinium yttrium garnets which have microwave applications. Gadolinium compounds are used as green phosphors in color television picture tubes. Because of its magnetic properties, gadolinium is also used in intravenous radiocontrast agents in magnetic resonance imaging (MRI). |
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Reactions
| Reaction with air: mild, ⇒ Gd2O3 | Reaction with 6 M HCl: mild, ⇒ H2, GdCl3 |
| Reaction with 15 M HNO3: mild, ⇒ Gd(NO3)3 | Reaction with 6 M NaOH: |
Compounds
| Oxide(s): Gd2O3 | Chloride(s): GdCl3 |
| Hydride(s): GdH2, GdH3 |
Radius
| Atomic radius: 180 pm | Ionic radius (1+ ion): pm |
| Ionic radius (2+ ion): pm | Ionic radius (3+ ion): 107.8 pm |
| Ionic radius (2- ion): pm | Ionic radius (1- ion): pm |
Conductivity
| Thermal conductivity: 10.6 W m-1 K-1 | Electrical conductivity: 0.8 x 106 S m-1 |
Abundance & Isotopes
| Abundance earth's crust: 5.2 parts per million by weight, 0.7 parts per million by moles | |
| Abundance solar system: 2 parts per billion by weight, 10 parts per trillion by moles | |
| Cost, pure: $20 per 100g | |
| Cost, bulk: $12 per 100g | |
| Source: Gadolinium is not found free in nature but is found in a number of minerals: mainly monazite and bastnasite. Commercially, gadolinium is isolated by ion exchange and solvent extraction. It can also be produced by the reduction of anhydrous gadolinium fluoride with calcium metal. | |
| Isotopes: Gadolinium has 27 isotopes whose half-lives are known, with mass numbers 137 to 164. Of these, six are stable, 154Gd, 155Gd, 156Gd, 157Gd 158Gd and 160Gd The most abundant isotope is 158Gd at 24.8%. | |
