Keychain Pu Plutonium.

<div>   </div> <div> <strong> Atomic number <span class = "Apple-tab-span" style = "white-space: pre;"> </span>             94 </strong> </div> <div> <strong> Atomic mass <span class = "Apple-tab-span" style = "white-space: pre;"> </span>             244 </strong> </div> <div> <strong> Density, kg / m? <span class = "Apple-tab-span" style = "white-space: pre;"> </span> & nbsp ;         19840 </strong> </div> <div> <strong> Temperature</strong></div> <div> <strong> melting, ° С             <span class = "Apple-tab-span" style = "white-space: pre;"> </span>640</strong></div> <div>   </div> <div> Plutonium - Heavy a fragile radioactive metal of silvery-white color. </div> <div> Plutonium was discovered in 1940-41 by American scientists G. Seaborg, E. Macmillan, J. Kennedy and A. Wahl, who obtained an isotope of plutonium as a result of irradiation of uranium with heavy nuclei hydrogen - daytons. Named after the planet Pluto, like the predecessors of Plutonium in the periodic table - uranium and neptunium, the names of which also originated from the planets Uranus and Neptune. & Nbsp; </div> <div> Widely used in the production of nuclear weapons (the so-called "weapons plutonium "), fuel for civil and research nuclear reactors and as a source of energy for spacecraft. The first nuclear bomb in the world, created and tested in 1945 in the United States, used a plutonium charge. The first bomb tested by the USSR in 1949 was of the same type. </div> <div>. </div> <div>   </div>