Lanthanum is a soft, ductile, silvery-white metallic chemical element with symbol La and atomic number 57. It tarnishes rapidly when exposed to air and is soft enough to be cut with a knife. It gave its name to the lanthanide series, a group of 15 similar elements between lanthanum and lutetium in the periodic table:it is also sometimes considered the first element of the 6th-period transition metals.
Three reasons Lanthanum stands out
- 1
Used in high-strength alloys and cameras.
- 2
Its oxide is added to specialty optical glass to give it a very high refractive index for sharper lenses.
- 3
It is used to store hydrogen in nickel–metal hydride rechargeable batteries found in hybrid vehicles.
The element that began the rare-earth story
Lanthanum is soft, reactive, and usually found mixed with chemically similar lanthanides. Its compounds improve optical glass and serve in catalysts, while lanthanum-nickel alloys can store hydrogen. The name means “to lie hidden,” fitting an element concealed within a supposedly known mineral.