Keychain Th Thorium.

<div>   </div> <div> <strong> Atomic number <span class = "Apple-tab-span" style = "white-space: pre;"> </span>     90 </strong> </div> <div> <strong> Atomic mass <span class = "Apple-tab-span" style = "white-space: pre;"> </span>       232.04 </strong> </div> <div> <strong> Density, kg / m? <Span class = "Apple-tab-span" style = "white-space: pre;"> </span> & nbsp ;   11700 </strong> </div> <div> <strong> Temperature</strong></div> <div> <strong> melting, ° С         <span class = "Apple-tab-span" style = "white-space: pre;"> </span>1750</strong></div> <div>   </div> <div > Thorium is a gray, soft, malleable, ductile, weakly radioactive metal. Thorium was first isolated by J. Berzelius in 1828 from a mineral later called thorite (contains thorium silicate). </div> <div> Thorium was named by its discoverer after the god of thunder Thor in Scandinavian mythology. </div> <div> Thorinated cathodes are used in electron tubes, and thorium oxide - in magnetrons and high-power generator lamps. Thorium and its compounds are widely used in the composition of catalysts in organic synthesis, for alloying magnesium and other alloys, which have gained great importance in jet aircraft and rocket technology. Metallic thorium is used in thorium reactors. Radiation safety rules must be observed when working with thorium. </div> <div>   </div>