Lanthanum was discovered in 1839 by Swedish chemist Carl Gustaf Mosander, who separated it from a sample of cerium nitrate, hence uncovering a new element that had been “lying hidden” within the compound.
This discovery came as Mosander was able to distinguish lanthanum oxide (lanthana) from cerium compounds. The name lanthanum is derived from the Greek word ‘lanthanein’, meaning “to lie hidden,” reflecting its elusive nature and the difficulty in isolating it from other rare earth elements.
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- Symbol: La
- Atomic Number: 57
- Atomic Weight: 138.90547
- Element Classification: Lanthanide
- Discovered By: Carl Gustaf Mosander
- Discovery Date: 1839
- Name Origin: Greek: ‘lanthanein’ (to lie hidden)
- Density(g/cc): 6.145
- Melting Point: 920°C
- Boiling Point: 3464°C
- Appearance: Silvery-white, soft, malleable, and ductile metal
- Atomic Radius(pm): 187
Relation to Other Elements
Lanthanum is the first element in the series of lanthanides, a group of similar metals that are part of the rare earth elements. Lanthanides are known for their high magnetic susceptibility, conductivity, and reactivity to water. Lanthanum itself is often found in combination with other rare earth elements in various minerals, such as monazite and bastnasite, and is somewhat more abundant in the Earth’s crust than some of its fellow lanthanides. It exhibits an oxidation state of +3 in most of its compounds, similar to other lanthanides.
Natural Occurrence
Lanthanum is not found free in nature but occurs in small amounts in a wide range of minerals. The most important commercial sources are the rare earth minerals monazite and bastnasite, which contain lanthanum along with other lanthanides. These minerals are processed to separate and purify the individual rare earth elements.
Uses
Lanthanum has various applications, many of which exploit its optical and chemical properties:
- Batteries: Lanthanum is used in nickel-metal hydride (NiMH) rechargeable batteries, which are found in hybrid cars, laptops, and mobile phones.
- Catalysis: It is a component of catalysts used in petroleum refining for cracking, the process of breaking down large oil molecules into gasoline, diesel, and other products.
- Optics: Lanthanum oxide is added to glass to improve clarity and increase refractive index, making it valuable for camera lenses, telescopes, and other precision optical instruments.
- Electronics: Lanthanum is used in the manufacturing of certain types of electronic displays, including color television screens and fluorescent lamps.
- Metal Alloys: Lanthanum can be alloyed with steel and other metals to improve their malleability, resistance to impact, and ductility.
The discovery of lanthanum and the exploration of its properties have significantly contributed to advancements in technology, particularly in energy storage, refining processes, and the production of high-quality optical glass. Its wide range of applications underscores the importance of rare earth elements in modern industry and technology.