Keychain. Europium.

<div>   </div> <div> <strong> Atomic number <span class = "Apple-tab-span" style = "white-space: pre;"> </span>     63 </strong> </div> <div> <strong> Atomic mass     <span class = "Apple-tab-span" style = "white-space: pre;"> </span>151,96</strong></div> <div> <strong> Density, kg / m ? <span class = "Apple-tab-span" style = "white-space: pre;"> </span>   5260 </strong> </div> <div> <strong> Temperature </strong></div> <div> <strong> melting, ° С       <span class = "Apple-tab-span" style = "white-space: pre;"> </span>826</strong></div> <div>   </div> <div> Europium - silvery-white metal, easily oxidized in air. The first spectral lines, later attributed to europium, were observed by Crookes (1886) and Lecoq de Boisbaudran (1892). Demarcay discovered a band of the element's spectrum in samarium earth in 1896, and in 1901 he was able to isolate the element, described it and named it after Europe. </div>