List of Elements in the Lanthanide Series

The lanthanides or lanthanoid series is a group of transition metals located on the periodic table in the first row (period) below the main body of the table. The lanthanides are commonly referred to as the rare earth elements (REE), although many people group scandium and yttrium together under this label as well. Therefore, it's less confusing to call the lanthanides a subset of the rare earth metals.

The Lanthanides

Here's a list of the 15 elements that are lanthanides, which run from atomic number 57 (lanthanum, or Ln) and 71 (lutetium, or Lu):

• Lanthanum: symbol Ln, atomic number 57
• Cerium: symbol Ce, atomic number 58
• Praseodymium: symbol Pr, atomic number 59
• Neodymium: symbol Nd, atomic number 60
• Promethium: symbol Pm, atomic number 61
• Samarium: symbol Sm, atomic number 62
• Europium: symbol Eu, atomic number 63
• Gadolinium: symbol Gd, atomic number 64
• Terbium: symbol Tb, atomic number 65
• Dysprosium: symbol Dy, atomic number 66
• Holmium: symbol Ho, atomic number 67
• Erbium: symbol Er, atomic number 68
• Thulium: symbol Tm, atomic number 69
• Ytterbium: symbol Yb, atomic number 70
• Lutetium: symbol Lu, atomic number 71

Note that sometimes lanthanides are considered to be the elements following lanthanum on the periodic table, making it a group of 14 elements. Some references also exclude lutetium from the group because it has a single valence electron in the 5d shell.

Properties of the Lanthanides

Because the lanthanides are all transition metals, these elements share common characteristics. In pure form, they are bright, metallic, and silvery in appearance. The most common oxidation state for most of these elements is +3, although +2 and +4 are also generally stable. Because they can have a variety of oxidation states, they tend to form brightly colored complexes.

Lanthanides are reactive—readily forming ionic compounds with other elements. For instance, lanthanum, cerium, praseodymium, neodymium, and europium react with oxygen to form oxide coatings or tarnish after brief exposure to air. Because of their reactivity, pure lanthanides are stored in an inert atmosphere, such as argon, or kept under mineral oil.

Unlike other most other transition metals, the lanthanides tend to be soft, sometimes to the point where they can be cut with a knife. Additionally, none of the elements occurs free in nature. When moving across the periodic table, the radius of the 3+ ion of each successive element decreases; this phenomenon is called lanthanide contraction.

With the exception of lutetium, all of the lanthanide elements are f-block elements, referring to the filling of the 4f electron shell. Although lutetium is a d-block element, it's usually considered a lanthanide because it shares so many chemical properties with the other elements in the group.

Surprisingly, even though the elements are called rare earth elements, they aren't particularly scarce in nature. However, it's difficult and time-consuming to isolate them from each other from their ores, adding to their value.

Lastly, lanthanides are valued for their use in electronics, particularly television and monitor displays. They are also used in lighters, lasers, and superconductors, and to color glass, make materials phosphorescent, and even control nuclear reactions.

A Note About Notation

The chemical symbol Ln may be used to refer to any lanthanide in general, not specifically the element lanthanum. This may be confusing, especially in situations where lanthanum itself isn't considered a member of the group!