Lanthanides
Rare Earth elements (atomic numbers 57-71)
The Lanthanide elements include Lanthanum, Cerium, Praseodymium, Neodymium, Promethium, Samarium, Europium, Gadolinium, Terbium, Dysprosium, Holmium, Erbium, Thulium, Ytterbium, and Lutetium. -They are found in period 6. - Their compounds are used as catalysts in the production of petroleum and synthetic products. - Lanthanides are used in the production of lamps, lasers, magnets, phosphors, motion picture projectors, and X-ray intensifying screen -Lanthanide are silvery-white metals that tarnish when exposed to air, forming their oxides. -They are relatively soft metals but become somewhat harder as their atomic number increases. -Moving from left to right across the period (increasing atomic number), the radius of each lanthanide 3+ ion steadily decreases. This is known as the 'lanthanide contraction'. -They have high melting points and boiling points. -Lanthanides react in an exothermic reaction with H2. -The most rare earth compounds are strongly paramagnetic. -Many rare earth compounds fluoresce strongly under ultraviolet light. |
-Lanthanides react with water to liberate hydrogen (H2), slowly in cold/quickly upon heating. Lanthanides commonly bind to water.
-They react with H+ (dilute acid) to release H2 (rapidly at room temperature). -The magnetic moments of the lanthanide and iron ions oppose each other. -These elements also react readily with most nonmetals and form binaries on heating with most nonmetals -At elevated temperatures, many rare earths ignite and burn vigorously. -Lanthanides are very reactive. -The magnetic moments of the lanthanide and iron ions oppose each other. -They react readily with most nonmetals and form binaries on heating with most nonmetals -Lanthanides burn easily in air. -They are strong reducing agents. -Their compounds are generally ionic. -Uses: as flint in cigarettes and gas lighters in the conversion of crude oil into gasoline, kerosene, diesel, and heating oil as phosphors in color TV sets phosphors are chemicals that glow with various colors when struck by electrons to color ceramics in nuclear applications because they absorb neutrons |