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sodium

(Encyclopedia)sodium, a metallic chemical element; symbol Na [Lat. natrium]; at. no. 11; at. wt. 22.98977; m.p. 97.81℃; b.p. 892.9℃; sp. gr. 0.971 at 20℃; valence +1. Sodium is a soft, silver-white metal. Ext...

Darfur

(Encyclopedia)Darfur därˈfo͞or [key], region and former sultanate, W Sudan. The region is mountainous, dominated by the central massif of Jebel Marra, which rises to 10,130 ft (3,088 m). Much of the terrain is d...

insecticides

(Encyclopedia)insecticides, chemical, biological, or other agents used to destroy insect pests; the term commonly refers to chemical agents only. The liabilities of chemical insecticides have encouraged interest ...

smallpox

(Encyclopedia)smallpox, acute, highly contagious disease causing a high fever and successive stages of severe skin eruptions. Occurring worldwide in epidemics, it killed up to 40% of those who contracted it and acc...

Pontiac's Rebellion

(Encyclopedia)Pontiac's Rebellion, Pontiac's Conspiracy, or Pontiac's War, 1763–66, Native American uprising against the British just after the close of the French and Indian Wars, so called after one of its lea...

Bush, George Herbert Walker

(Encyclopedia)Bush, George Herbert Walker, 1924–2018, 41st President of the United States (1989–93), b. Milton, Mass., B.A., Yale Univ., 1948. Bush's handling of domestic affairs was less successful. The savi...

Reagan, Ronald Wilson

(Encyclopedia)Reagan, Ronald Wilson rāˈgən [key], 1911–2004, 40th president of the United States (1981–89), b. Tampico, Ill. In 1932, after graduation from Eureka College, he became a radio announcer and spo...

cell, in biology

(Encyclopedia)CE5 Animal cell cell, in biology, the unit of structure and function of which all plants and animals are composed. The cell is the smallest unit in the living organism that is capable of integrati...

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...

meson

(Encyclopedia)meson mēˈzŏn [key] [Gr.,=middle (i.e., middleweight)], class of elementary particles whose masses are generally between those of the lepton class of lighter particles and those of the baryon class ...