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protactiniumProtactinium has been called the mother of actinium, which is formed by the alpha decay of protactinium. The first discovery of protactinium was in 1913 by Kasimir Fajans and O. Göhring, who found the isotope protactinium-234m (half-life 1.2 min), a decay product of uranium-238; they named it brevium for its short life. Protactinium-231 was first identified in 1918 by Otto Hahn and Lisa Meitner and independently by Frederick Soddy and John A. Cranston; the name protoactinium was adopted at this time. In 1927, Aristid V. Grosse prepared the pentoxide, and in 1934 isolated the metal from a purified sample of oxide. The name protactinium was adopted in 1949 by the International Union of Pure and Applied Chemistry.
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- Periodic Table of the Elements: Protactinium
Periodic Table of the Elements: ProtactiniumAtomic Number:91Atomic Symbol:PaProtactiniumAtomic Weight:231.0359ElectronConfiguration:2 · 8 · 1832 · 209 · 2
- Pa
Pa, symbol for the element protactinium.
- Meitner, Lise
Meitner, Lise, 1878–1968, Austrian-Swedish physicist and mathematician. She was professor at the Univ. of Berlin (1926–33). A refugee from Germany after 1938, she became associated with the Un...
- actinide series
Actinide series, a series of radioactive metallic elements in Group 3 of the periodic table. Members of the series are often called actinides, although actinium (at. no. 89) is not always cons...
- thorium
Thorium [from Thor], radioactive chemical element; symbol Th; at. no. 90; at. wt. 232.0381; m.p. about 1,750°C; b.p. about 4,790°C; sp. gr. 11.7 at 20°C; valence +4.Thorium is a soft, ductile,...
- uranium
Uranium, radioactive metallic chemical element; symbol U; at. no. 92; at. wt. 238.0289; m.p. 1,132°C; b.p. 3,818°C; sp. gr. 19.1 at 25°C; valence +3, +4, +5, or +6. Uranium is a hard, dense, m...
- Elements (table)
ElementsElementSymbolAtomic NumberAtomic Weight1Melting Point(Degrees Celsius)Boiling Point(Degrees Celsius)1 Parentheses indicate most stable isotope.actiniumAc89227.02781050.3200....
