Lanthanide
![Lanthanide oxides: clockwise from top center: praseodymium, cerium, lanthanum, neodymium, samarium and gadolinium.](/Images/godic/202501/23/Rareearthoxides1719.jpg")
![A solution of 4% holmium oxide in 10% perchloric acid, permanently fused into a quartz cuvette as a wavelength calibration standard](/Images/godic/202501/23/HoOxideSolution1719.jpg")
The lanthanide /ˈlænθənaɪd/ or lanthanoid /ˈlænθənɔɪd/ series of chemical elements comprises the fifteen metallic chemical elements with atomic numbers 57 through 71, from lanthanum through lutetium. These fifteen lanthanide elements, along with the chemically similar elements scandium and yttrium, are often collectively known as the rare earth elements.