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protactinium

(Encyclopedia)protactinium prōˌtăktĭnˈēəm [key], radioactive chemical element; symbol Pa; at. no. 91; mass number of most stable isotope 231; m.p. greater than 1,600℃; b.p. 4,026℃; sp. gr. 15.37 (calcula...

palladium, chemical element

(Encyclopedia)palladium [Gr. Pallas, goddess of wisdom], metallic chemical element; symbol Pd; at. no. 46; at. wt. 106.42; m.p. 1,554℃; b.p. 2,970℃; sp. gr. 12.02 at 20℃; valence +2, +3, or +4. Palladium is a...

alkyne

(Encyclopedia)CE5 Alkynes alkyne ălˈkīn [key], any of a group of aliphatic hydrocarbons whose molecules contain one or more carbon-carbon triple bonds (see chemical bond). Alkynes with one triple bond have t...

hassium

(Encyclopedia)hassium hăsˈēəm, häsˈ– [key], artificially produced radioactive chemical element; symbol Hs; at. no. 108; mass number of most stable isotope 277; m.p., b.p., sp. gr., and valence unknown. Situ...

Yar'Adua, Umaru Musa

(Encyclopedia)Yar'Adua, Umaru Musa o͞omäˈro͞o mo͞oˈsä yär ädo͞oˈä [key], 1951–2010, Nigerian politician, president of Nigeria (2007–10). Born into a family active in Nigerian political and military ...

carboxyl group

(Encyclopedia)carboxyl group kärbŏkˈsĭl [key], in chemistry, functional group that consists of a carbon atom joined to an oxygen atom by a double bond and to a hydroxyl group, OH, by a single bond. Carboxylic a...

Carey, Peter

(Encyclopedia)Carey, Peter, 1943–, Australian novelist, b. near Melbourne. Carey's combination of science fiction and fantasy motifs with a realistic style, displayed in the short stories in The Fat Man in Histor...

anatomy

(Encyclopedia)anatomy ənătˈəmē [key], branch of biology concerned with the study of body structure of various organisms, including humans. Comparative anatomy is concerned with the structural differences of pl...

voice, sound produced by living beings

(Encyclopedia)voice, sound produced by living beings. The source of the sound in human speaking and singing is the vibration of the vocal cords, which are inside the larynx, and the production of the sounds is call...

livermorium

(Encyclopedia)livermorium, artificially produced radioactive chemical element; symbol Lv; at. no. 116; mass number of most stable isotope 292; m.p., b.p., sp. gr., and valence unknown. Situated in Group 16 of the p...