Sentence:  <WSD>Ytterbium</WSD> is a silvery, soft, malleable, and ductile metal with a lustrous metallic shine. It is slightly reactive in air or water at room temperatures. <WSD>Ytterbium</WSD> is located next to last of the rare-earths in the lanthanide series. 
Meaning of the word marked with <WSD> tags:  A metallic chemical element ("symbol" Yb) with an atomic number of 70.