The lanthanide /ˈlænθənaɪd/ or lanthanoid /ˈlænθənɔɪd/ series o chemical elements[1] comprises the fifteen metallic chemical elements wi atomic nummers 57 through 71, frae lanthanum through lutetium.[2][3][4] These fifteen lanthanide elements, alang wi the chemically seemilar elements scandium an yttrium, are eften collectively kent as the rare yird elements.