Uranium
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Uranium is a chemical element; it has symbol U and atomic number 92. It is a silvery-grey metal in the actinide series of the periodic table. A uranium atom has 92 protons and 92 electrons, of which 6
HE Uranium C
Various militaries use depleted uranium as high-density penetrators.
Uranium glass glowing under UV light
The uranium glaze on a ceramic artwork glowing under UV light.
Protactinium
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Protactinium is a chemical element; it has symbol Pa and atomic number 91. It is a dense, radioactive, silvery-gray actinide metal which readily reacts with oxygen, water vapor, and inorganic acids. I
Uranium
…Tantalum Tungsten Rhenium Osmium Iridium Platinum Gold Mercury (element) Thallium Lead Bismuth Polonium Astatine Radon Francium Radium Actinium Thorium Protactinium Uranium Neptunium Plutonium Americium Curium Berkelium Californium Einsteinium Fermium Mendelevium Nobelium Lawrencium Rutherfordium Dubnium Seaborgium…
Sample of protactinium-231 in a glass vial
Dmitri Mendeleev's 1871 periodic table with a gap for protactinium on the bottom row of the chart, between thorium and uranium
Protactinium occurs in uraninite ores.