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organometallic chemistry
(Encyclopedia)organometallic chemistry, the reactions and use of a class of compounds (R-M) that contain a covalent bond between carbon and metal. They are prepared either by direct reaction of the metal with an or...lawrencium
(Encyclopedia)lawrencium, artificially produced radioactive chemical element; symbol Lr; at. no. 103; mass number of most stable isotope 262; m.p. about 1,627℃; b.p. and sp. gr. unknown; valence +3. Lawrencium is...Gay-Lussac, Joseph Louis
(Encyclopedia)Gay-Lussac, Joseph Louis zhôzĕfˈ lwē gā-lüsäkˈ [key], 1778–1850, French chemist and physicist. He was professor in Paris at the Sorbonne, at the Polytechnic School, and at the Jardin des Pla...boric acid
(Encyclopedia)boric acid, any one of the three chemical compounds, orthoboric (or boracic) acid, metaboric acid, and tetraboric (or pyroboric) acid; the term often refers simply to orthoboric acid. The acids may be...hafnium
(Encyclopedia)hafnium hăfˈnēəm [key], metallic chemical element; symbol Hf; at. no. 72; at. wt. 178.49; m.p. about 2,227℃; b.p. 4,602℃; sp. gr. 13.31 at 20℃; valence +4. Hafnium is a lustrous, ductile, si...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...Qinghai
(Encyclopedia)Qinghai or Tsinghai both: chĭngˈhīˈ [key], province (2010 pop. 5,626,722), c.279,000 sq mi (722,797 sq km), W China. Xining is the capital. Qinghai lies in the Tibetan highlands at an average elev...semiconductor
(Encyclopedia)CE5 N-type and P-type crystals: In a pure silicon crystal each silicon atom (Si) is surrounded by four valence electrons. In the N-doped semiconductor, illustrated in the left-hand figure, some sil...Ossetia
(Encyclopedia)Ossetia älänˈyä [key], Ossetian Iryston, region of the central Caucasus, divided between the Republic of Georgia and the Russian Federation. On the northern slope is North Ossetia-Alania (1990 est...ammonia
(Encyclopedia)ammonia, chemical compound, NH3, colorless gas that is about one half as dense as air at ordinary temperatures and pressures. It has a characteristic pungent, penetrating odor. Ammonia forms a minute ...Browse by Subject
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