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Hahn, Otto
(Encyclopedia)Hahn, Otto ôˈtō hän [key], 1879–1968, German chemist and physicist. His important contributions in the field of radioactivity include the discovery of several radioactive substances, the develop...Berzelius, Jöns Jakob, Baron
(Encyclopedia)Berzelius, Jöns Jakob, Baron bərzēˈlēəs; Swed. yöns yäˈkôp bĕrsāˈlĭəs [key], 1779–1848, Swedish chemist, M.D. Univ. of Uppsala, 1802. He was noted for his work as teacher at the medic...radon
(Encyclopedia)radon rāˈdŏn [key], gaseous radioactive chemical element; symbol Rn; at. no. 86; mass no. of most stable isotope 222; m.p. about −71℃; b.p. −61.8℃; density 9.73 grams per liter at STP; vale...half-life
(Encyclopedia)half-life, measure of the average lifetime of a radioactive substance (see radioactivity) or an unstable subatomic particle. One half-life is the time required for one half of any given quantity of th...francium
(Encyclopedia)francium frănˈsēəm [key] [from France], radioactive chemical element; symbol Fr; at. no. 87; mass no. of most stable isotope 223; m.p. about 27℃ (estimated); b.p. 677℃ (estimated); sp. gr. unk...pitchblende
(Encyclopedia)pitchblende pĭchˈblĕndˌ [key], dark, lustrous, heavy mineral, a source of radium and uranium. Largely natural uranium oxides, triuranium octaoxide (U3O8) and uranium dioxide (UO2), it usually cont...astatine
(Encyclopedia)astatine ăsˈtətēn, –tĭn [key] [Gr.,=unstable], semimetallic radioactive chemical element; symbol At; at. no. 85; at. wt. of most stable isotope 210; m.p. 302℃ (estimated); b.p. 337℃ (estima...radioactivity
(Encyclopedia)CE5 Effects of a magnetic field on the products of radioactivity CE5 Disintegration series: Radioactive decay of radium-226 into lead-206 radioactivity, spontaneous disintegration or decay of t...tracer
(Encyclopedia)tracer, an identifiable substance used to follow the course of a physical, chemical, or biological process. In chemistry the ideal tracer has the same chemical properties as the molecule it replaces a...lanthanum
(Encyclopedia)lanthanum lănˈthənəm [key] [Gr.,=to lie hidden], metallic chemical element; symbol La; at. no. 57; at. wt. 138.90547; m.p. about 920℃; b.p. about 3,460℃; sp. gr. 6.19 at 25℃; valence +3. Lan...Browse by Subject
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