Plutonium
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Plutonium is a chemical element; it has symbol Pu and atomic number 94. It is a silvery-gray actinide metal that tarnishes when exposed to air, and forms a dull coating when oxidized. The element norm
A sample of plutonium metal, shaped like a ring to prevent nuclear criticality
Various oxidation states of plutonium in solution
Plutonium pyrophoricity can cause it to look like a glowing ember under certain conditions.
Twenty micrograms of pure plutonium hydroxide
Neptunium
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Neptunium is a chemical element; it has symbol Np and atomic number 93. A radioactive actinide metal, neptunium is the first transuranic element. It is named after Neptune, the planet beyond Uranus in
Plutonium
…to form the new element with atomic number 94 and atomic weight 238 (half-life 88 years). Since uranium had been named after the planet Uranus and neptunium after the planet Neptune, element 94 was named after Pluto, which at the time was also considered a planet. Wartime secrecy prevented the University…
Sample of neptunium-237 in a glass vial
This nickel-clad neptunium sphere was used to experimentally determine the critical mass of Np at Los Alamos National Lab.
The 60-inch cyclotron at the Lawrence Radiation Laboratory, University of California, Berkeley, in August 1939
Neptunium ions in solution