Gadolinium
Symbol |
Name |
Atomic Number |
Atomic Weight |
Group Number |
Gd |
Gadolinium |
64 |
157.25 |
1 |
Standard Sate: solid at 298 K
Color: silvery white
Gadolinium is silvery white, has a metallic lustre, and is is malleable and ductile. It is ferromagnetic (strongly attracted by a magnet).The metal is relatively stable in dry air, but in moist air it tarnishes with the formation of a loosely adhering oxide film which "spalls" 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.
(Gd), chemical element, rareearth metal of transition Group IIIb of the
periodic table. Silvery white and moderately ductile, the metal reacts
slowly with oxygen and water. Below 17 C it is ferromagnetic and at
very low temperatures, superconducting. Credit for the discovery of
gadolinium is shared by J.-C.-G. de Marignac and P.-�. Lecoq de
Boisbaudran. Marignac separated (1880) a new rare earth (metallic
oxide) from the mineral samarskite; Lecoq de Boisbaudran obtained
(1886) a fairly pure sample of the same earth, which with Marignac's
assent he named gadolinia, after a mineral in which it occurs that in
turn had been named for the Finnish chemist Johan Gadolin.
Gadolinium occurs in many minerals along with the other rare earths
but is obtained primarily from monazite. It is found also in the
products of nuclear fission. Commercial separation depends upon
ion-exchange techniques. The metal has been produced by
thermoreduction of the anhydrous chloride or fluoride by calcium.
Gadolinium is used for certain electronic components and
high-temperature refractories and as an alloying agent. H.
Kamerlingh Onnes first produced (1923) temperatures below 1 K by
magnetic cooling using gadolinium sulfate. Gadolinium has the
highest absorption cross section for thermal neutrons of any natural
isotope of any element (49,000 barns), which suggests its use in
nuclear reactor control rods. The seven natural stable isotopes have
mass numbers between 152 and 160; the species of highest mass
numbers are more abundant.
Gadolinium is trivalent in all of its compounds; it behaves as a typical
rare earth. Its salts are white, and its solutions are colourless. atomic
number 64 atomic weight 157.250 melting point 1,311 C boiling point
3,233 C specific gravity 7.898 (25 C) valence 3 electronic config.
2-8-18-25-9-2 or (Xe)4f 75d16s2
"gadolinium" Encyclop�dia Britannica Online.
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