|a ductile malleable silvery-white ferromagnetic element of the lanthanide series of metals: occurs principally in monazite and bastnaesite. Symbol: Gd; atomic no: 64; atomic wt: 157.25; valency: 3; relative density: 7.901; melting pt: 1313±°C; boiling pt: 3273°C (approx.)|
|[C19: New Latin, from |
|a calculus or concretion found in the stomach or intestines of certain animals, esp. ruminants, formerly reputed to be an effective remedy for poison.|
|a printed punctuation mark (‽), available only in some typefaces, designed to combine the question mark (?) and the exclamation point (!), indicating a mixture of query and interjection, as after a rhetorical question.|
gadolinium gad·o·lin·i·um (gād'l-ĭn'ē-əm)
A malleable, ductile metallic rare-earth element. Atomic number 64; atomic weight 157.25; melting point 1,314°C; boiling point 3,264°C; specific gravity 7.8; valence 3.
|gadolinium (gād'l-ĭn'ē-əm) Pronunciation Key
A silvery-white, malleable, ductile metallic element of the lanthanide series that has seven natural isotopes and 11 artificial isotopes. Two of the natural isotopes, Gd 155 and Gd 157, are the best known neutron absorbers. Gadolinium is used to improve the heat and corrosion resistance of iron, chromium, and various alloys and in medicine as a contrast medium for magnetic resonance imaging and as a radioisotope in bone mineral analysis. Atomic number 64; atomic weight 157.25; melting point 1,312°C; boiling point approximately 3,000°C; specific gravity from 7.8 to 7.896; valence 3. See Periodic Table.
((Gd), chemical element, rare-earth metal of the lanthanoid series 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.-E. 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.
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