plutonium

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Silvery-white, radioactive, metallic element of the actinide series, atomic number 94, relative atomic mass 239.13. It occurs in nature in minute quantities in pitchblende and other ores, but is produced in quantity only synthetically. It has six allotropic forms (see allotropy) and is one of the fissile elements (elements capable of splitting into other elements – others include thorium and uranium). Plutonium dioxide, PuO₂, a yellow crystalline solid, is the compound most widely used in the nuclear industry. It was believed to be inert until US researchers discovered in 1999 that it reacts very slowly with oxygen and water to form a previously unknown green crystalline compound that is soluble in water.

Red represents work. Yellow symbolizes justice. The design is based on the French tricolour. Green stands for solidarity. Effective date: 10 November 1958. >>