Lanthanides

Lanthanides are a set of 15 naturally occurring metallic elements, whose atomic numbers fall between 57 (lanthanum) and 71 (lutetium). These elements all have their 4f sublevel filled. Lanthanides exhibit similarities in physical and chemical properties, and they have many industrial uses.

List of Lanthanides

• 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

The lanthanides are located in block 5d of the periodic table. The first 5d transition element is either lanthanum or lutetium, depending on how you interpret the periodic trends of the elements. Sometimes only the lanthanides, and not the actinides, are classified as rare earths; however, even the scarce rare earths (e.g., europium, lutetium) are more common than platinum-group metals.

Several of these lanthanides form during fission processes with uranium and plutonium materials.

Common Properties of the Lanthanides

Lanthanides share the following common properties:

• Tarnishes in the air, forming its oxides.
• Soft metals. Hardness increases somewhat as the atomic number rises.
• Each lanthanide 3+ ion’s radius decreases from left to right across the period (increasing atomic number). This is known as ‘lanthanide shrinkage.’
• Melting points and boiling points are high.
• They’re very reactive.
• React with water to release hydrogen (H2) gradually, but rapidly after heating
• React with H+ (dilute acid) to release H2 (rapidly at room temperature).
• React in an exothermic reaction with H2.
• Burn easily in air.
• They are strong reducing agents.
• Their compounds are generally ionic.
• At elevated temperatures, many rare earths ignite and burn vigorously.
• Most rare earth compounds are strongly paramagnetic.
• Many rare earth compounds fluoresce strongly under ultraviolet light.
• Lanthanide ions tend to be pale colors, resulting from weak, narrow, forbidden f x f optical transitions.
• The magnetic moments of the lanthanide and iron ions oppose each other.
• The lanthanides react readily with most nonmetals and form binaries on heating with most nonmetals.