Lanthanides and actinides.
“Europium is a lanthanide with the symbol Eu and atomic number 63. It is a steel-gray metal about...Europium
“Thorium is a chemical element with the symbol Th and atomic number 90. Thorium is a highly...Thorium
“Neodymium is a lanthanide with the symbol Nd and atomic number 60. Also classified as a rare...Neodymium