Is iad a n-ainmneacha agus siombailí ceimiceacha ná scandium (Sc), yttrium (Y), lanthanum (La), cerium (Ce), praseodimiam (Pr), neodimiam (Nd), promethium (Pm), samarium (Sm), europium (Eu) , gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), lutetium (Lu). Is iad na huimhreacha adamhacha atá acu ná 21 (Sc), 39 (Y), 57 (La) go 71 (Lu).