Definition of Lanthanides
The lanthanides are a series of 15 metallic chemical elements with atomic numbers 57 (lanthanum) through 71 (lutetium), typically shown as a separate row at the bottom of the periodic table. They are characterized by the filling of the 4f electron shell, which gives them similar chemical properties and distinct electronic configurations.
Key Properties and Characteristics
These elements are soft, silvery-white metals that tarnish rapidly in air. They are highly reactive, generally forming trivalent (3+) cations in compounds. A defining feature is their unique magnetic and optical properties, stemming from their partially filled 4f orbitals, which lead to diverse applications.
Applications of Lanthanides
Lanthanides are vital in many high-tech applications. They are used in the production of powerful permanent magnets (e.g., in headphones, hard drives, and electric vehicle motors), catalysts in petroleum refining, phosphors in display screens (TVs, smartphones), and lasers. They also find use in medical imaging agents and specialized alloys.
'Rare Earths' Misnomer
While often referred to as 'rare earth elements,' many lanthanides are relatively abundant in the Earth's crust. The term 'rare earth' refers more to the difficulty and cost of extracting and purifying them from their mineral ores due to their chemical similarity, rather than their actual scarcity.