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nihonium

(Encyclopedia)nihonium nĭhōˈnēəm [key], artificially produced radioactive chemical element; symbol Nh; at. no. 113; mass number of most stable isotope 284; m.p., b.p., sp. gr., and valence unknown. Situated in...

San Luis Potosí, state, Mexico

(Encyclopedia)San Luis Potosí sän lo͞oēsˈ pōtōsēˈ [key], state (1990 pop. 2,003,187), 24,417 sq mi (63,240 sq km), central Mexico. San Luis Potosí is the capital. Most of the state lies on the eastern tab...

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...

roentgenium

(Encyclopedia)roentgenium, artificially produced radioactive chemical element; symbol Rg; at. no. 111; mass number of most stable isotope 280; m.p., b.p., sp. gr., and valence unknown. Situated in Group 11 of the p...

tellurium

(Encyclopedia)tellurium tĕlo͝orˈēəm [key] [Lat.,=earth], semimetallic chemical element; symbol Te; at. no. 52; at. wt. 127.60; m.p. 450℃; b.p. 990℃; sp. gr. 6.24 at 20℃; valence −2, +4, or +6. Telluriu...

meitnerium

(Encyclopedia)meitnerium mītnĭrˈēəm [key], artificially produced radioactive chemical element; symbol Mt; at. no. 109; mass number of most stable isotope 276; m.p., b.p., sp. gr., and valence unknown. Situated...

pewter

(Encyclopedia)pewter, any of a number of ductile, silver-white alloys consisting principally of tin. The properties vary with the percentage of tin and the nature of the added materials. Lead, when added, imparts a...

Zacatecas, state, Mexico

(Encyclopedia)Zacatecas säkätāˈkäs [key], state (1990 pop. 1,276,329), 28,125 sq mi (72,844 sq km), N central Mexico. Zacatecas is the capital. Lying on the central plateau, Zacatecas is a state of semiarid pl...

mineral

(Encyclopedia)mineral, inorganic substance occurring in nature, having a characteristic and homogeneous chemical composition, definite physical properties, and, usually, a definite crystalline form. A few of the mi...

nucleosynthesis

(Encyclopedia)nucleosynthesis or nucleogenesis, in astronomy, production of all the chemical elements from the simplest element, hydrogen, by thermonuclear reactions within stars, supernovas, and in the big bang at...

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