Gadolinium

Gadolinium, ₆₄Gd

Gadolinium
Pronunciation	/ˌɡædəˈlɪniəm/ ​(GAD-ə-LIN-ee-əm)
Appearance	silvery white
Standard atomic weight Ar°(Gd)
	157.25±0.03[1] 157.25±0.03 (abridged)[2]
Gadolinium in the periodic table
Hydrogen Helium Lithium Beryllium Boron Carbon Nitrogen Oxygen Fluorine Neon Sodium Magnesium Aluminium Silicon Phosphorus Sulfur Chlorine Argon Potassium Calcium Scandium Titanium Vanadium Chromium Manganese Iron Cobalt Nickel Copper Zinc Gallium Germanium Arsenic Selenium Bromine Krypton Rubidium Strontium Yttrium Zirconium Niobium Molybdenum Technetium Ruthenium Rhodium Palladium Silver Cadmium Indium Tin Antimony Tellurium Iodine Xenon Caesium Barium Lanthanum Cerium Praseodymium Neodymium Promethium Samarium Europium Gadolinium Terbium Dysprosium Holmium Erbium Thulium Ytterbium Lutetium Hafnium Tantalum Tungsten Rhenium Osmium Iridium Platinum Gold Mercury (element) Thallium Lead Bismuth Polonium Astatine Radon Francium Radium Actinium Thorium Protactinium Uranium Neptunium Plutonium Americium Curium Berkelium Californium Einsteinium Fermium Mendelevium Nobelium Lawrencium Rutherfordium Dubnium Seaborgium Bohrium Hassium Meitnerium Darmstadtium Roentgenium Copernicium Nihonium Flerovium Moscovium Livermorium Tennessine Oganesson – ↑ Gd ↓ Cm europium ← gadolinium → terbium
Atomic number (Z)	64
Group	f-block groups (no number)
Period	period 6
Block	f-block
Electron configuration	[Xe] 4f7 5d1 6s2
Electrons per shell	2, 8, 18, 25, 9, 2
Physical properties
Phase at STP	solid
Melting point	1585 K ​(1312 °C, ​2394 °F)
Boiling point	3546 K ​(3273 °C, ​5923 °F)
Density (at 20° C)	7.899 g/cm3 [3]
when liquid (at m.p.)	7.4 g/cm3
Heat of fusion	10.05 kJ/mol
Heat of vaporization	301.3 kJ/mol
Molar heat capacity	37.03 J/(mol·K)
Vapor pressure (calculated) P (Pa) 1 10 100 1 k 10 k 100 k at T (K) 1836 2028 2267 2573 2976 3535
Atomic properties
Oxidation states	0,[4] +1, +2, +3 (a mildly basic oxide)
Electronegativity	Pauling scale: 1.20
Ionization energies	1st: 593.4 kJ/mol 2nd: 1170 kJ/mol 3rd: 1990 kJ/mol
Atomic radius	empirical: 180 pm
Covalent radius	196±6 pm
Spectral lines of gadolinium
Other properties
Natural occurrence	primordial
Crystal structure	​hexagonal close-packed (hcp) (hP2)
Lattice constants	a = 363.37 pm c = 578.21 pm (at 20 °C)[3]
Thermal expansion	−21.4×10−6/K (at 20 °C) 11.1×10−6/K (at 100 °C)[3][a]
Thermal conductivity	10.6 W/(m⋅K)
Electrical resistivity	α, poly: 1.310 µΩ⋅m
Magnetic ordering	ferromagnetic–paramagnetic transition at 293.4 K
Molar magnetic susceptibility	+755000.0×10−6 cm3/mol (300.6 K)[5]
Young's modulus	α form: 54.8 GPa
Shear modulus	α form: 21.8 GPa
Bulk modulus	α form: 37.9 GPa
Speed of sound thin rod	2680 m/s (at 20 °C)
Poisson ratio	α form: 0.259
Vickers hardness	510–950 MPa
CAS Number	7440-54-2
History
Naming	after the mineral gadolinite (itself named after Johan Gadolin)
Discovery	Jean Charles Galissard de Marignac (1880)
First isolation	Lecoq de Boisbaudran (1886)
Isotopes of gadolinium v e
Main isotopes[6] Decay abun­dance half-life (t1/2) mode pro­duct 148Gd synth 86.9 y[7] α 144Sm 150Gd synth 1.79×106 y α 146Sm 152Gd 0.2% 1.08×1014 y α 148Sm 153Gd synth 240.6 d ε 153Eu 154Gd 2.18% stable 155Gd 14.8% stable 156Gd 20.5% stable 157Gd 15.7% stable 158Gd 24.8% stable 160Gd 21.9% stable
Category: Gadolinium view talk edit | references

Gadolinium is a chemical element; it has symbol Gd and atomic number 64. Gadolinium is a silvery-white metal when oxidation is removed. It is a malleable and ductile rare-earth element. Gadolinium reacts with atmospheric oxygen or moisture slowly to form a black coating. Gadolinium below its Curie point of 20 °C (68 °F) is ferromagnetic, with an attraction to a magnetic field higher than that of nickel. Above this temperature it is the most paramagnetic element. It is found in nature only in an oxidized form. When separated, it usually has impurities of the other rare-earths because of their similar chemical properties.

Gadolinium was discovered in 1880 by Jean Charles de Marignac, who detected its oxide by using spectroscopy. It is named after the mineral gadolinite, one of the minerals in which gadolinium is found, itself named for the Finnish chemist Johan Gadolin. Pure gadolinium was first isolated by the chemist Paul-Émile Lecoq de Boisbaudran around 1886.

Gadolinium possesses unusual metallurgical properties, to the extent that as little as 1% of gadolinium can significantly improve the workability and resistance to oxidation at high temperatures of iron, chromium, and related metals. Gadolinium as a metal or a salt absorbs neutrons and is, therefore, used sometimes for shielding in neutron radiography and in nuclear reactors.

Like most of the rare earths, gadolinium forms trivalent ions with fluorescent properties, and salts of gadolinium(III) are used as phosphors in various applications.

Gadolinium(III) ions in water-soluble salts are highly toxic to mammals. However, chelated gadolinium(III) compounds prevent the gadolinium(III) from being exposed to the organism and the majority is excreted by healthy^[8] kidneys before it can deposit in tissues. Because of its paramagnetic properties, solutions of chelated organic gadolinium complexes are used as intravenously administered gadolinium-based MRI contrast agents in medical magnetic resonance imaging.

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